Sayyiduna Abdullah bin Ja'far (may Allah be pleased with them both) relates that when the news of the martyrdom of Ja'far (may Allah be pleased with him) came, the Messenger of Allah (peace and blessings be upon him) said: "Prepare food for the family of Ja'far, for a matter has come upon them that will keep them occupied."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 13801