He made the vow conditional on

Q: I made a vow that if Allah granted me such and such thing, I would observe I`tikaf (seclusion for worship in a Masjid) for one night and recite the whole Qur'an in Al-Masjid Al-Nabawy (the Prophet’s Mosque in Al-Madinah) along with fasting the day after that night. This was my vow. Allah (Exalted be He) made my wish come true. Consequently, I went to Madinah to fulfill my vow but found the doors of Al-Masjid Al-Nabawy Al-Sharif closed; as they are always closed after the `Isha' (Night) Prayer. I was, thus, not able to fulfill my vow.

A: If the reality is as you mentioned, you could observe your I`tikaf in Al-Masjid Al-Haram (the Sacred Mosque in Makkah) in Makkah, and fast the day after, as you know that performing Salah (Prayer) in Al-Masjid Al-Haram in Makkah is more rewarded than performing it in Al-Masjid Al-Nabawy. As for your desire to recite the whole Qur'an in that night, you could do so in Al-Masjid Al-Nabawy during the daytime and at night before its doors are closed. (Part No. 23; Page No. 249) If you do this in Al-Masjid Al-Haram, that would be sufficient and more rewarded.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.