A curse (also called an imprecation, malediction, hex, execration, malison, anathema, or commination) is any expressed wish that some form of adversity or misfortune will befall or attach to one or more persons, a place, or an object.
It is related al-Ash'ath ibn Qays (al-Amali, al-Saduq, p. 185) went blind for refusing to bear witness to what happened at Ghadeer.
Some also mention Zayd ibn Arqam although this might be in error.
Real Muslim prays for the good for every one. We should pray for those wronged us and did injustice on us to be guided to the truth and to leave wrong way to the right way.
'We don't curse any believer. We only curse the enemies of Allah (SWT), the Prophet (SAWA) and Ahlul Bayt (AS) who are in fact the enemies of mankind.