What is the ruling regarding the divorce pronouncement I uttered, and will it take effect if I hit my daughter again, knowing that I regret it and do not wish to divorce her?

A Muslim should avoid using divorce (talaq (definition)), due to the severe consequences that result from it. Your statement to your wife: "By divorce, if you hit her again in front of me or in my absence, you have no one to blame but yourself," is an oath of divorce.

The majority of scholars are of the opinion that if one breaks such an oath, divorce occurs. Some of them stipulated that this must be done with remembrance (i.e., not forgetting the oath). Some scholars, however, held that in this matter, reference is made to the intention of the one who swore the oath. If he intended divorce, it occurs. But if he did not intend divorce, yet intended to urge his wife to do something or prevent her from it, then it is an oath that requires an expiation for an oath (kaffarat al-yamin (definition)). This latter view is the preponderant one.

What matters is the intention at the time of uttering the divorce statement. If you intended to prevent her from hitting your daughter and did not intend divorce, then this has the ruling of an oath. If she returns and hits her, then an expiation for an oath is binding upon you. However, if your intention at the time of uttering what you mentioned was divorce, then you do not have the power to retract this oath. If your wife hits your daughter while she remembers your oath, then a divorce (talaqa) occurs.