Ibn Hajar Makki has written in Asnial Matalib fi Silatul Aqarib that one day Amir’ul-Mu’minin (a.s) began to weep. When people asked him about it he said that seven days have passed but he did not have a guest. “I am fearful that maybe Allah has considered me degraded.”
Amir’ul-Mu’minin (a.s) used to say, “Three things are most dear to me: Hospitality, Jihad with the sword and keeping fast on a hot day.”
Whenever he had a guest, the Imam used to be exceeding happy and did not leave any stone unturned in rendering him all the comforts and facilities. He asked the guest about his favorite dish and ordered that only that one be prepared for him. However insignificant a person his guest may be, he used to seat him next to himself. Himself he ate that same barley bread softened in water and grains of salt, but he served his guests the most delicious foods.
Reference :Akhlaq al-A’imma, Morals & Manners of the Holy Imams