For the purpose of repentance, is it obligatory to inform my parents about money I wrongfully took from them when I was a teenager, knowing that I asked for their forgiveness in Ramadan, and I cannot return the money now? Also, is it permissible to wear clothes I bought with that money for prayer?

Firstly, it is not permissible to take money from a father or anyone else without their knowledge, for this constitutes aggression and consuming wealth unjustly. This is supported by the verse: "O you who have believed, do not consume one another's wealth unjustly but only [in lawful] business by mutual consent" (Quran 4:29), and prophetic hadiths that prohibit taking a person's money without their willing consent. An exception to this is when a child takes what they need for their expenses from their miserly father's money.

Secondly, one must repent to Allah Almighty by feeling remorse and resolving not to return to the sin, and by seeking absolution from the father or returning the money to him. Asking for forgiveness is sufficient, but if that is difficult, then the money must be returned to him. If there is no money, it remains an obligation until it can be found.

Thirdly, if clothing was purchased with illicit money, it is considered usurped. According to the school of Imam Ahmad, prayer in such clothing is not valid until absolution is sought or the money is returned. The majority of scholars, however, hold that prayer is valid, though the sin remains. It appears that prayer in such clothing is valid because it was purchased on credit and then paid for with illicit money. When money becomes available, what was taken from the father's money must be returned.