Majma al-Zawaid — Hadith 3984

Sayyiduna al-Harith bin Uqaysh (may Allah be pleased with him) narrates: We were with Sayyiduna Abu Barzah (may Allah be pleased with him), and he narrated to us this hadith from the Prophet (peace and blessings be upon him), that he said: "Any two Muslims (husband and wife) whose four children die, Allah Almighty will admit them both (husband and wife) into Paradise by the grace of His mercy." The people said: "O Messenger of Allah! And if there are three?" The Prophet (peace and blessings be upon him) said: "And if three (children have died, the same reward will be attained)." The people said: "And if there are two?" The Prophet (peace and blessings be upon him) said: "And if there are two (the same reward will be attained)." The Prophet (peace and blessings be upon him) said: "A man of my Ummah will be so huge in Hell that he will fill one of its corners, and there will be a man of my Ummah through whose intercession (as many people as the members of) the tribe of Mudar will enter Paradise."
Imam Ahmad recorded it as a hadith narrated from Sayyiduna Abu Barzah (may Allah be pleased with him), and its narrators are thiqat (trustworthy).