You will see after me favoritism
Ibn Mas'ud, May Allah be pleased with him, reported:"The Messenger of Allah, may the peace and blessings of Allah be upon him, said, "You will see after me favoritism and things which you will disapprove of." They said: "What do you order us to do (under such circumstances)?" He replied, "Discharge your obligations and ask your rights from Allah".
Favoritism is the opposite of altruism, it is a degeneration, ungratefulness to the blessings of Allah, and contradicting the natural instinct.
This is the absolute evil even if it is mixed up with some benefits for oneself. It is the inclination to be followed and the stinginess to be obeyed by the wicked.
It is to love oneself, that is called in our modern language selfishness, a term attributed to the pronoun "I", meaning that the stingy one says: myself, I only love myself, and I serve no one.
The Prophet, may the peace and blessings of Allah be upon him, informed that favoritism would occur after him.
In his era, may the peace and blessings be upon him, altruism was prevalent of the morals among his honorable righteous companions, be them of the immigrants or of the Ansaar.
Allah has described the Ansar as altruistic despite the fact that they are in need for what they give to their fellow Muslims do, but do not you assume that they are singled out with this noble manner excluding the immigrants who embraced Islam before them.
This noble description of the Ansar does not contradict the fact that it befits others than them, especially those who have been driven out of their homes and their property with no legal cause and have favored the Prophet, may the peace and blessings of Allah be upon him, with all their belongings.