Hadith 113

وعن أبي سعيد الخدري رضي الله عنه قال : خرج رجلان في سفر فحضرت الصلاة وليس معهما ماء فتيمما صعيدا طيبا فصليا ثم وجدا الماء في الوقت ،‏‏‏‏ فأعاد أحدهما الصلاة والوضوء ،‏‏‏‏ ولم يعد الآخر ،‏‏‏‏ ثم أتيا رسول الله صلى الله عليه وآله وسلم فذكرا ذلك له ،‏‏‏‏ فقال للذي لم يعد : « أصبت السنة وأجزأتك صلاتك » وقال للآخر:« لك الأجر مرتين» . رواه أبو داود والنسائي.
Narrated Abu Sa'id al-Khudri (RAA): Two men set out on a journey and when the time of Salat (prayer) came they had no water. They performed Tayammum with clean earth and prayed. Later on they found water within the time of the prayer. One of them repeated his prayer with ablution but the other did not repeat. Then they came to Allah's Messenger (ﷺ), and related the matter to him. Addressing himself to the one who did not repeat, he said, "You followed the Sunnah and your (first) prayer was enough for you."[9] He said to the one who performed ablution and repeated: "For you there is a double reward". [Reported by Abu Dawud and An-Nasa'i]
Hadith Reference بلوغ المرام / 113
Hadith Grading محدثین: حسن
Hadith Takhrij «أخرجه أبوداود، الطهارة، باب في المتيمم يجد الماء بعد ما يصلي في الوقت، حديث:338، والنسائي، الطهارة، حديث:433.»
Related hadith on this topic
Explanation & Benefits
Shaykh Safi ur-Rahman Mubarakpuri
Benefits and Issues:
➊ From this hadith, it is understood that if one has performed prayer after doing tayammum (dry ablution), and later, within the same prayer time, water becomes available, then in such a case, there is no need to repeat the prayer. This is the position of the four jurists (fuqaha’ arba‘a).
➋ What is the explanation for the person who repeated the prayer receiving double reward? The reason is that one reward was for performing the prayer, and the other was for exercising ijtihad (independent juristic reasoning).
➌ Although the ijtihad was not correct, nevertheless, one reward is given for the effort and striving.
Source: Bulugh al-Maram: Commentary by Safiur Rahman Mubarakpuri, Page: 113
Hafiz Muhammad Ameen
433. Commentary:

➊ The fundamental principle is that tayammum, in the absence of water, is like ablution (wudu); therefore, there is absolutely no need to repeat the prayer. The ijtihad (independent reasoning) of this person was correct, which is why it was called “sunnah.” As for the other person, although his ijtihad was not correct, since his intention was good, he endured greater hardship, and he performed a righteous deed twice, therefore he is deserving of reward. However, now repeating (the prayer) is not permitted because the issue has become clear and the sunnah has been established. Now, there is neither a need nor permission for ijtihad. And it is prohibited to perform a single obligatory prayer twice with the intention of it being obligatory both times.

➋ The meaning of «سَهْمِ جَمْعٍ» is: double reward, i.e., for the first prayer and for the second as well. Some scholars have interpreted it as “a share of the army,” i.e., “booty.”
Source: Sunan Nasa'i: Translation and Benefits by Shaykh Hafiz Muhammad Amin Hafizullah, Page: 433
Hafiz Nadeem Zaheer
Fiqh al-Hadith:
➊ In the case where water is not available, the prayer performed with tayammum suffices; there is no need to repeat it, even if water becomes available during the time of prayer itself, as is made clear by the hadith.
➋ The person who performed ablution (wudu) and then repeated the prayer is given glad tidings of “double reward” due to this double effort.
➌ In the absence of a clear text, ijtihad (independent reasoning) can be exercised, but when the texts of the Qur’an and Sunnah are present, there is no room for ijtihad. Likewise, after the evidences become clear, that ijtihad is rendered void. Therefore, in this matter, instead of following the ijtihad of a Companion (radi Allahu anhu), the Sunnah of the Noble Prophet (sallallahu alayhi wa sallam) will be acted upon.
Source: Monthly Magazine al-Hadith Hazro, Issue No. 133, Page: 8