Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) says: The Messenger of Allah (peace and blessings be upon him) bought a caravan that came with some uqiyahs of gold, and he (peace and blessings be upon him) gave it in charity to the widows of Banu Abd al-Muttalib, and said: "I do not buy anything whose price I do not have with me."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 11693