Riyad-us-Saliheen 1553
Abud-Darda' (May Allah be pleased with him) said: The Messenger of Allah (PBUH) said, "Those who frequently resort to cursing (people) would neither be accepted as witnesses nor as intercessors on the Day of Resurrection."
[Muslim]
The habit of taunting and cursing makes a man sinful. Such a person has no value with Allah, and his testimony and intercession will not be considered on the Day of Judgement.