Is it permissible to say, "May our Lord grant us repentance," when warning someone about committing a forbidden act, and what is the ruling on this statement?

Allah's repentance towards His servant has two meanings: Allah's enabling of the servant to repent, and Allah's acceptance of the servant's repentance.

The servant's repentance occurs between two acts of repentance from Allah: a preceding one (enabling and inspiring), and a subsequent one (accepting and rewarding), as explained by Ibn al-Qayyim, Ibn Uthaymeen, and al-Sadi in their exegesis of Allah's saying: (Then He turned to them that they might repent).

Accordingly, if a person who persists in sin says: "May our Lord turn to us in repentance," and intends the second meaning (acceptance of repentance), he is a liar, because he has not repented. However, if he intends the first meaning (enabling to repent), then it is a good supplication that includes acknowledging shortcomings and sin, and it is beneficial like any supplication. Through it, forgiveness may be granted, or evil averted, or good attained.

Seeking forgiveness while persisting in sin is not considered repentance, as the scholars have stated, but it does not contradict seeking mere forgiveness without repentance.