Prophet Muhammad (peace be upon him) said:
"People’s deeds are presented before Allah on Mondays and Thursdays, and then every slave (of Allah) is granted forgiveness (of minor sins) if he does not associate anything with Allah in worship. But the person in whose heart there is rancor against his brother, will not be pardoned. With regard to them, it is said twice: ‘Hold these two until they are reconciled.’ ’’
Narrated by Abu Hurairah (r.a.) Muslim Hadith No. 1593 quoted from Riyad-us-Saliheen Volume 2 Chapter 17 The book of the prohibited actions.
Commentary: To entertain enmity without any major lawful reason is akin to inviting the displeasure of Allah. May Allah save us from it.