On the authority of Abu Hurayrah (may Allah be pleased with him), who said that the Messenger of Allah (peace and blessings of Allah be upon him) said:

"If Allah has loved a servant [of His], He calls Gabriel (on whom be peace) and says: 'I love So-and-so, therefore love him.'" He (the Prophet - peace and blessings of Allah be upon him) said: "So Gabriel loves him. Then he (Gabriel) calls out in heaven, saying: 'Allah loves So-and-so, therefore love him.' And the inhabitants of heaven love him." He (the Prophet - peace and blessings of Allah be upon him) said: "Then acceptance is established for him on earth. And if Allah has abhorred a servant [of His], He calls Gabriel and says: 'I abhor So-and-so, therefore abhor him.' So Gabriel abhors him. Then Gabriel calls out to the inhabitants of heaven: 'Allah abhors So-and-so, therefore abhor him.'" He (the Prophet - peace and blessings of Allah be upon him) said: "So they abhor him, and abhorrence is established for him on earth."

[Muslim (also by al-Bukhari, Malik, and at-Tirmidhi).]