Mu'jam Kabir Tabarani 10085 — We used to speak during the prayer; one

Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) narrates: We used to speak during the prayer; one of us would greet another with salam, and one of us would indicate his need by gesture. One day I came while the Prophet (peace and blessings be upon him) was praying, and I greeted him with salam, but he did not return my greeting. All my past and recent concerns began to come to my mind. When he had finished, he said: "Allah, the Mighty and Majestic, brings about whatever new ruling He wills from His command, and He has brought about the new ruling that you should not speak during the prayer."