Sayyiduna Abdullah (may Allah be pleased with him) narrates that we used to greet the Prophet (peace and blessings of Allah be upon him) with salam during prayer. He narrated similar to the previous hadith, and said that the Prophet (peace be upon him) used to reply to our salam (later the ruling was changed), and he said: "Indeed, there is engagement in prayer." (Therefore, do not reply to salam verbally while in prayer.) I asked Ibrahim, "How do you reply to salam?" He replied, "I reply in my heart."