Midrash su Giudici 5:2

R. Joshua b. Levi said: "He who answers Amen Yehei Shemei Rabba Mebarach with all his fervor will cause any evil dispensation passed on him, to be torn (nulliified); for it is said (Judg. 5, 2.) When decreed punishments had been set aside in Israel, then did the people offer themselves willingly, Praise ye the Lord. Why were decreed punishments set aside? Because Praise ye the Lord." R. Chiya b. Abba, in the name of R. Jochanan, said: "Even if there be some idolatry in him, he will also be forgiven; for it is written (Ib.) When decreed punishments were set aside (Pra'oth), and it is also written (Ex. 32, 25.) That it had become unruly (Parua)." Resh Lakish said: "He who answers Amen with all his fervor will have the gates of Eden opened for him, as it is said (Is. 26, 2.) Open ye the gates, that there may enter the righteous nation, which guardeth the truth. Do not read Shomer Emunim (which guardeth the truth) but read it Seomrim Amen (which say Amen)." What is the meaning of Amen? R. Chanina said: "The abbreviation of 'God, faithful king.'"