Allah, the Exalted, informs about His believing servants, who work for righteous deeds- deeds that are in accordance with the legislation of Muhammad (SAW)- that He plants love for them in the heart of His righteous servants. This is something that is absolutely necessary and there is no avoiding it.
Ibn Abi Hatim reported that Abu Hurayrah said that the Prophet said,
Whenever Allah loves a servant of His, He calls Jibril (saying), ”Verily, I love so-and-so, so love him”
Then, Jibril calls out into the heavens and love for him descends among the people of the earth.
That is the meaning of the statement of Allah, the Mighty and Sublime:
Verily, for those who have believed and done righteous deeds, the Most Merciful will appoint for them affection.
This was also reported by Muslim and At-Tirmidhi and At-Tirmidhi said, ”Hassan Sahih”
Culled from Tafsir Ibn Kathir.