Is one who curses another who has wronged him by praying that God prolong his life, worsen his deeds, expose him in this world and the Hereafter, and take his soul in the embrace of a harlot, sinful?

It is permissible for a Muslim to supplicate against an oppressor who is also a Muslim. However, forgiveness and pardon are better, for "whoever pardons and makes reconciliation – his reward is due from Allah." It is not permissible to supplicate for a sin or severing ties of kinship, nor to transgress in supplication by asking for something greater than the offense or for a sin, based on His (Allah's) saying: "Then whoever has transgressed against you, then transgress against him in like manner as he has transgressed against you."