Bukhari

Benefits and Issues:
Relevance between the Chapter and the Hadith:
Imam Bukhari rahimahullah established the chapter: What supplication should the imam and the follower recite when rising from bowing (ruku)? However, the hadith he mentioned does not mention the follower (muqtadi); rather, it only mentions the imam. The relevance between the hadith and the chapter is as follows: Imam Bukhari rahimahullah is alluding to those narrations in which there is a clear command that the imam is appointed so that he may be followed; therefore, when the imam rises from bowing, it is necessary for the follower to also rise in accordance with the imam.

In the mentioned chapter, Imam Bukhari rahimahullah has only mentioned the hadith regarding the imam, but by adding «من خلفه» in the chapter heading, he has indicated towards the followers and thus expressed his own inclination.

Imam Bukhari rahimahullah, under the chapter heading, mentions the hadith of Abu Hurairah radi Allahu anhu, in which there are clear words that the Prophet sallallahu alayhi wa sallam, when raising his head, would say «سمع الله لمن حمده» and then «اللهم ربنا لك الحمد». Although the follower is not mentioned, according to hadith «انما جعل الامام ليؤتم به» and hadith «صلوا كما رايتموني اصلي», the follower will also say the same. Thus, the relevance between the chapter heading and the hadith is established here.

◈ Ibn Rashid rahimahullah says:
«بأنه اشار الي التذكير بالمقدمات لتكون الاحاديث عند الاستنباط نصب عيني المستنبط فقد تقدم حديث ’’انما جعل الامام ليؤتم به“ و حديث صلوا كما رآيتموني اصلي» [فتح الباري، ج2، ص245]

◈ Imam Ata rahimahullah says:
«يجمعهما الامام و الماموم احب الي» [معرفة السنن و الاثار، ج2، ص12]
“I prefer that both the imam and the follower are included in this ruling.”

◈ Ibn al-Mulaqqin rahimahullah says:
This supplication «سمع الله لمن حمده» is not exclusive to the imam (rather, the follower is also included). [التوضيح ج 6۔ ص 175]

Benefit:
When the imam rises from bowing, he should recite «سمع الله لمن حمده», and the followers should also repeat these same words.

◈ Imam Daraqutni rahimahullah says in Sunan Daraqutni:
«عن ابي هريرة رضى الله عنه ان النبى صلى الله عليه وسلم قال، اذا قال الامام سمع الله لمن حمده فليقل من ورائه سمع الله لمن حمده .» [سنن الدار قطني ج1 رقم الحديث 1270، اور ده ابن الجوزي فى التحقيق ج1 ص386 واسناده صحيح]
The Messenger of Allah sallallahu alayhi wa sallam said: When the imam says «سمع الله لمن حمده», then those behind him (the followers) should also say «سمع الله لمن حمده .».

◈ Hafiz Ibn Hajar rahimahullah says:
«وقد ورد فى ذالك حديث عن أبى هريرة أيضًا أخرجه الدارقطني بلفظ : كنا إذا صلينا خلف رسول الله صلى الله عليه وسلم فقال سمع الله لمن حمده قال من وراءه سمع الله لمن حمده .» [فتح الباري ج2 ص359]
“Indeed, regarding this issue, there is a hadith from Abu Hurairah radi Allahu anhu, which Imam Daraqutni has narrated: When we would pray behind the Messenger of Allah sallallahu alayhi wa sallam, he would say «سمع الله حمده», and the followers behind him would also say these same words.”

◈ Imam Daraqutni rahimahullah has also mentioned another narration in his Sunan through «ابن عون قال محمد ! إذا قال الإمام سمع الله لمن حمده قال من خلفه سمع الله لمن حمده ربنا ولك الحمد .» [سنن الدارقطني ج1 رقم 1291]
In this narration, there is reconciliation between the two reports in which it is mentioned: When the imam says «سمع الله لمن حمده», then you should say «ربنا ولك الحمد». If one reflects, there is no contradiction between these two narrations, because the hadith in which it is mentioned for the followers to say «ربنا ولك الحمد» does not prohibit saying «سمع الله لمن حمده», since the well-known principle is: the absence of mention does not necessitate the absence of the thing itself.
Therefore, the follower may say «سمع الله لمن حمده ربنا ولك الحمد». «والله اعلم»

Hadith Commentary:
From this hadith, the statement of the imam is established, but the statement of the follower (muqtadi) is established in such a way that it is necessary for the follower to follow the imam.
As is mentioned in another narration.
In other chains of this same hadith, it is narrated from Abu Hurairah (radi Allahu anhu) that when the imam says "Sami‘a Allahu liman hamidah," those behind him should also say along with the imam, "Rabbana wa laka al-hamd," etc.

Hadith Commentary:
(1)
In the terminology of the hadith scholars, "Samia Allahu liman hamidah" is called "tasmi‘" and "Rabbana wa laka al-hamd" is called "tahmid." This hadith is evidence that tasmi‘ is to be recited upon rising from bowing (ruku‘), and tahmid is to be recited after standing upright from ruku‘. It is also understood that the imam should perform both acts, because the prayer of the Messenger of Allah (sallallahu alayhi wa sallam) about which Abu Hurairah (radi Allahu anhu) is narrating this detail should be understood as being in the context of leading the prayer, since most of the noble Companions (radi Allahu anhum) who observed and reported the Prophet (sallallahu alayhi wa sallam) praying, did so while he was leading the prayer. Therefore, the imam will say both tasmi‘ and tahmid.
(Fath al-Bari: 2/353)
(2)
The imam, the follower (muqtadi), and the individual praying alone (munfarid) should all say tasmi‘ when rising from ruku‘, and tahmid after standing upright, as is established from the Messenger of Allah (sallallahu alayhi wa sallam) in the aforementioned hadith. Furthermore, the imam is appointed so that he may be followed. However, it is narrated from Anas (radi Allahu anhu) that the Messenger of Allah (sallallahu alayhi wa sallam) said:
"When the imam says 'Samia Allahu liman hamidah,' you should say 'Rabbana wa laka al-hamd.'"
(Sahih al-Bukhari, al-Adhan, Hadith: 732)
To infer from this hadith that the follower should not say "Samia Allahu liman hamidah" and the imam should not say "Rabbana wa laka al-hamd" is in no way correct, because it is established from authentic ahadith that the Messenger of Allah (sallallahu alayhi wa sallam) used to say both phrases and commanded to pray in this manner. However, it should be clear that the purpose of this hadith of Anas (radi Allahu anhu) is not to specify what the imam and the follower should say at this point, but merely to indicate that the follower's tahmid should come after the imam's tasmi‘, as explained by Allamah al-Albani.
(Sifat Salat al-Nabi sallallahu alayhi wa sallam, p. 135)
At this point, there is an objection that the presented hadith only establishes the imam's practice of saying both tasmi‘ and tahmid, but does not establish what the follower should say.
The answer is that the follower is obligated to follow the imam, so he too, following the imam, will perform both tasmi‘ and tahmid.
Moreover, the Messenger of Allah (sallallahu alayhi wa sallam) said: "Pray as you have seen me praying."
This hadith also necessitates that the follower should combine both tasmi‘ and tahmid.
In this regard, a hadith is also presented which Imam al-Daraqutni has narrated: Abu Hurairah (radi Allahu anhu) said that when we prayed behind the Messenger of Allah (sallallahu alayhi wa sallam) and he said "Samia Allahu liman hamidah," those praying behind him would also say "Samia Allahu liman hamidah." However, Imam al-Daraqutni himself clarified that these words are not authentic; rather, the preserved narration is that the followers behind him would say "Rabbana wa laka al-hamd."
(Fath al-Bari: 2/365)
And Allah knows best.

1061. Commentary: It is understood that when the imam rises from bowing (ruku‘), he should say «سمعَ اللَّهُ لمن حمدَهُ» as well as «رَبَّنَا وَلَكَ الْحَمْدُ». Similarly, a person praying alone should also say both phrases. Imam Malik rahimahullah is not in favor of the imam saying «رَبَّنَا وَلَكَ الْحَمْدُ». He is of the opinion that this is a response to «سمعَ اللَّهُ لمن حمدَهُ», therefore, only the follower (muqtadi) will say this phrase, and the imam will say only «سمعَ اللَّهُ لمن حمدَهُ». However, this is contrary to explicit hadiths. Such contextual appropriateness is sought only in cases where there is no explicit text (clear Qur’an or hadith) mentioned.

Benefits and Issues:
➊
It is narrated in Sahih al-Bukhari that when the Messenger of Allah (sallallahu alayhi wa sallam) would rise from bowing (ruku‘), he would say: (Sami‘a Allahu liman hamidah).
Then, when he stood up straight, he would say: (Rabbana laka al-hamd)
or (Rabbana wa laka al-hamd).
(Sahih al-Bukhari, al-Adhan, Chapter: The Takbir when rising from prostration, Hadith: 788)

➋
The introductory phrase is narrated in various forms.
Whichever way it is recited, it is correct.
That is, (Rabbana laka al-hamd)
or (Rabbana wa laka al-hamd) (Allahumma rabbana wa laka al-hamd) (Allahumma rabbana wa laka al-hamd).
See: (Sahih Muslim, al-Salat, Chapter: What is said when raising the head from bowing, Hadith: 477, 476)