It is only appropriate for a person to go to others' doors for ten reasons

Commander of the Faithful (ʿas) said, "The sages of bygone times would say that it is only appropriate for a person to go to others' doors for ten reasons. The first type of these doors belongs to the house of God - Mighty and Exalted - to perform one's worship of Him, standing to fulfill for Him His right, and to give Him what is obligatory in His service. The second are the doors of the kings whose obedience is tied to the obedience to God - Mighty and Exalted; those kings whose obedience is mandatory, whose benefit is great, and whose wrath is severe. The third are the doors of scholars from whom one may benefit both of the knowledge of the religion and the world. The fourth are the doors of people of generosity and effort, who spend their wealth seeking to praise God and desiring the afterlife. The fifth are the doors of the simple-minded, who require help in calamities and demand aid from them for their needs. The sixth are the doors of nobility who may be approached seeking gifts, generosity, and fulfillment of one's needs. The seventh are the doors of those who can be depended on to give good opinions, counsel, strengthen one's resolve, and help undertake preparations. The eighth are the doors of your brothers when it is mandatory to meet with them and necessary to fulfill their rights. The ninth are the doors of enemies in which you dwell, coaxing their evils to repel them, pushing them away with cunning, gentleness, courtesy, and visiting their enemies. The tenth are the doors of those who are beneficial to visit; you receive their good manners, and you are inclined to converse with them."