Abu Dawud Book 2, Hadith Number 924.

Narated By Abdullah ibn Mas’ud : We used to salute during prayer and talk about our needs. I came to the Apostle of Allah (PBUH) 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 Apostle of Allah (PBUH) 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.