My Story: On the day of "trawih" prayer at masjid ghufran. I was praying with my friends in the mosque. When "imam" (the leader of prayer) finishing the "AL-Fatihah" chanting, when part last of the chant, it is "AMIN" everybody must say the word. When,i say the word "AMIN", and a voice beside me also said "Amin" but nodody beside me, i know beside me no one only at the back. So, i continue praying and ignore the voice.