Abdullah bin Buhayna · The Book of Forgetfulness (In Prayer)

"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…

"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.'"

The Messenger of Allah (ﷺ) offered one of the afternoon prayers with five (rak'ahs), and it was said to him: "Has something been added to the prayer?" He said: 'Why are you asking?' They said: 'You prayed five.' He said: 'I am only human, I forget as you forget, and I remember as you remember.' Then he prostrated twice then ended his prayer.