‎Shaykh Muḥammad Ṣāliḥ al-'Uthaymīn رحمه الله said: ‎"It is not permissible to postpone making up fast (from the last Ramaḍān) to the point that the second Ramaḍān enters without an excuse. This is because of the statement of 'Aa'ishah رضي الله عنها: "I had to fast to make from Ramaḍān and I was not able to do so except in Sha'bān." ‎[Reported by Bukhārī] ‎[مجالس شهر رمضان ص ٥٩]