Allah describes His own mercy as vast beyond imagination. In the Quran He says, 'O My servants who have transgressed against themselves, do not despair of the mercy of Allah. Indeed, Allah forgives all sins' (39:53). This is not a conditional promise for small sins only — it is addressed to those who have wronged their own souls, whatever the wrong may be. A hadith qudsi puts it even more strikingly: Allah tells the son of Adam that were his sins to reach the clouds of the sky, and he then sought forgiveness, Allah would forgive him (Tirmidhi 3540). The only sin Allah has said He will not forgive is dying upon shirk without repentance — and even that door is wide open the moment a person turns back sincerely, at any point before death. So no, Allah's mercy toward a repentant heart has no ceiling. The size of the sin never outweighs the size of His forgiveness; despair is the real danger, not the sin itself.
Q&A · Repentance & Sin
Does Allah's mercy really have no limits, no matter how great my sins are?
References
39:53Tirmidhi 3540
Informational, not a personal fatwa. Consult a qualified scholar for rulings on your situation.