´It was narrated that Ibn Mas'ud said:` "We used to greet the Prophet (ﷺ) with salam and he would return our salam, until we came back from the land of Ethiopia. I greeted him with salam and he did not return my greeting,a nd I started to wonder why. So I sat down; and when he finished praying, he said: 'Allah (SWT) decrees what He wills, and He has decreed what we should not speak during the prayer.'"
Hadith Referenceسنن نسائي / كتاب السهو / 1222
Hadith Gradingالألبانی:حسن صحيح | زبیر علی زئی:إسناده حسن
´It was narrated that Abdullah bin Mas'ud said:` "I used to come to the Prophet (ﷺ) when he was praying, and I would greet him with Salam, he would return my greeting. Then I came to him when he was praying, and he did not return my greeting. When he said the Taslim, he pointed to the people and said: "Allah (SWT) has decreed that in the prayer you should not speak except to remember Allah (SWT), and it is not appropriate for you, and that you should stand before Allah (SWT) with obedience.'"
Hafiz Muhammad Ameen
1221. Commentary: This hadith is narrated from Imam Sufyan al-Thawri rahimahullah by his two students, Ibn Abi Ghaniyyah (Yahya ibn Abd al-Malik) and Qasim ibn Yazid. However, the wording of this hadith is that of Qasim ibn Yazid, while Ibn Ghaniyyah narrates this hadith by meaning (not verbatim).
Source: Sunan Nasa'i: Translation and Benefits by Shaykh Hafiz Muhammad Amin Hafizullah, Page: 1221
Narrated Abdullah ibn Masud: We used to salute during prayer and talk about our needs. I came to the Messenger of Allah ﷺ and found him praying. I saluted him, but he did not respond to me. I recalled what happened to me in the past and in the present. When the Messenger of Allah ﷺ finished his prayer, he said to me: Allah, the Almighty, creates new command as He wishes, and Allah, the Exalted, has sent a fresh command that you must not talk during prayer. He then returned my salutation.
Shaykh Umar Farooq Saeedi
924. Commentary: Replying to the greeting (salam) verbally had been abrogated, but replying by gesture is permissible and Sunnah, as will be mentioned in the following ahadith.
Source: Sunan Abu Dawood – Commentary by Shaykh Umar Farooq Saeedi, Page: 924