Majma al-Zawaid — Hadith 13939

Sayyiduna Qays bin Makhramah (may Allah be pleased with him) says: The Prophet (peace and blessings be upon him) was born in the Year of the Elephant, and between the War of Fijar and the Year of the Elephant there was a gap of twenty years. The narrator says: People called it the War of Fijar because they had transgressed and declared lawful things that they used to hold unlawful. Between the War of Fijar and the building of the Ka'bah there was an interval of fifteen years, and between the building of the Ka'bah and the commissioning of the Prophet (peace and blessings be upon him) there was a gap of five years; so the Prophet (peace and blessings be upon him) was commissioned at the age of forty. (Allamah al-Haythami says:) I say: Imam al-Tirmidhi has recorded from it only the part about his (peace and blessings be upon him) birth.
Al-Tabarani recorded it; its chain contains a narrator, Ja'far bin Mihran al-Sabbak, who has been declared trustworthy and has also been criticised; the remaining narrators of this report are thiqat (trustworthy).