Muhammad bin Umar bin Ali bin Abi Talib (may Allah have mercy on him) narrates from his father, and he from his grandfather (Sayyiduna Ali bin Abi Talib (may Allah be pleased with him)), that the Messenger of Allah (peace and blessings be upon him) said to him: "Do not delay three things: 1. the prayer, when its time has come; 2. the funeral, when it is present; 3. the marriage of a widow, when a suitable match (kuf') is found."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النكاح / 13757