Sayyiduna Wa'il (may Allah be pleased with him) said: I prayed with the Messenger of Allah (peace and blessings be upon him), and I heard him, when he recited "nor of those who go astray," say "Amin," keeping his voice low with it. He placed his right hand on the left, and gave the salam to the right and to the left.
Hadith Referenceالمعجم الكبير للطبراني / باب الواو / 18332