Sunan Abi Dawud 527

Muhammad ibn al-Muthanna narrated to us: Muhammad ibn Jahdam narrated to me: Ismaʿil ibn Jaʿfar narrated to us, from ʿUmarah ibn Ghaziyyah, from Khubayb ibn ʿAbd al-Rahman ibn Isaf, from Hafs ibn ʿAsim ibn ʿUmar, from his father, from his grandfather ʿUmar ibn al-Khattab (may Allah be pleased with him), that the Messenger of Allah (peace and blessings be upon him) said: ‘When the caller to prayer says “Allah is greatest, Allah is greatest,” one of you should reply, “Allah is greatest, Allah is greatest.” When he says, “I testify that there is no god but Allah,” reply, “I testify that there is no god but Allah.” When he says, “I testify that Muhammad is the Messenger of Allah,” reply, “I testify that Muhammad is the Messenger of Allah.” When he says, “Come to prayer,” reply, “There is no might nor power except through Allah.” When he says, “Come to salvation,” reply, “There is no might nor power except through Allah.” When he says, “Allah is greatest, Allah is greatest,” reply, “Allah is greatest, Allah is greatest.” When he says, “There is no god but Allah,” and he says it from his heart, he will enter Paradise.’