Sayyiduna Abdullah bin Mas’ud (may Allah be pleased with him) narrates: Previously, we used to greet the Prophet (peace and blessings of Allah be upon him) with salam. At that time, when he was performing prayer, he would reply to our salam. This was before we came (to Madinah Munawwarah) from the land of Abyssinia. When we returned from Najashi, I presented myself before him. He was performing prayer at that time. I greeted him with salam, but he did not reply to my salam. Various apprehensions came to my mind. I sat down waiting for him. When he completed the prayer, I submitted: O Messenger of Allah (peace and blessings of Allah be upon him)! I greeted you with salam while you were performing prayer, but you did not reply to my salam. (In one narration, these words are mentioned:) Previously, you used to reply to salam. The Prophet (peace and blessings of Allah be upon him) said: Allah, the Exalted, can make a new decision as He wills, and He has now given a new command: we will not speak during prayer.