It is narrated from Sayyiduna Wa'il al-Hadrami (may Allah be pleased with him) that he prayed behind the Prophet (peace and blessings be upon him). When he recited "nor of those who go astray" [Surah al-Fatihah: 7], he said "Amin" and kept his voice low with it. He placed his right hand on his left hand, and gave the salam to the right and to the left.
Hadith Referenceالمعجم الكبير للطبراني / باب الواو / 18329