Inability to remember the number of times an oath is broken

Q 1: many years ago, I vowed not to do a certain thing and that if I were to do it, I would donate a very large sum that I perhaps would not be able to afford. I made this oath to deter myself from committing that act. Unfortunately, years later, I breached my oath so many times that I do not know their number. However, Allah (Exalted be He) blessed me to make sincere Tawbah (repentance to Allah). I performed Hajj and abandoned that act entirely, all praise be to Allah Alone. My question now is what must I do to expiate for the oath that I have broken? I do not exactly remember the number of times I have broken my oath. It may be worth mentioning that I usually make a lot of Istighfar (seeking forgiveness from Allah) because of this matter. Now I undertake Da`wah (calling to Islam), advise people to perform Salah (Prayer) in congregation, enjoin Ma`ruf (that which is judged as good, beneficial, or fitting by Islamic law and Muslims of sound intellect), forbid Munkar (that which is unacceptable or disapproved of by Islamic law and Muslims of sound intellect), (Part No. 23; Page No. 41) offer voluntary night Salahs (Prayers), and recite the Qur'an. Again, I can not afford the sum that I took an oath to donate. What should I do? May Allah reward you with the best.

A: If the matter is as you mentioned, it will be Wajib (obligatory) on you to make Kaffarah (expiation) for breaking your oath. Such a Kaffarah is to feed ten needy people, clothe them, or free a believing slave. Only if you are unable to fulfill any of these options, may you observe Sawm (Fast) for three days.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.