Sayyiduna Ibn Abbas (may Allah be pleased with them both) said: Two men came to the Prophet of Allah (peace and blessings be upon him), both with the same need. One of them gave the greeting of salam, and the Messenger of Allah (peace and blessings be upon him) noticed a bad odour from his mouth. He (peace and blessings be upon him) said to him: "Do you not use the miswak?" He said: I do use it, but I have not had any food for three days. So he (peace and blessings be upon him) ordered a man, who fed him and fulfilled his need.
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 12558