Imam an-Nawāwī, may Allāh have mercy upon him in the Majmū’ said:
(Subsection) The ‘ulamā’ who are reckoned, has ijmā’ (consensus) that it is compulsory for one who left the prayer on purpose to perform qadhā’. Abū Muhammad ‘Ālī Bin Hazm differed from them. He said:
He is not in a position to ever perform qadhā’ for them. And his doing so will never be śah (accepted).
Rather, he should make numerous good deeds (al-khair), and voluntary prayers so that his mīzan (scale) becomes heavy on the day of judgement. He should make istighfār to Allāh most High and make tawbah.
This is what he mentioned despite differing with the ijmā’, which is bātil considering the proofs. He expounded on it in length, deducing proofs for it but what he mentioned are absolutely not proofs. Amongst the dalīl that shows the obligatory nature of qadhā’ is the Hadīth of Abū Hurairah, may Allāh be pleased with him,
أَنَّ النَّبِيَّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ أَمَرَ الْمُجَامِعَ فِي نَهَارِ رَمَضَانَ أَنْ يَصُومَ يَوْمًا مَعَ الْكَفَّارَةِ
That the Prophet, Salutations of Allāh and His Peace upon him, instructed the one who had intercourse on a day in Ramadhān to fast a day with the kaffārah (expiation).
Which is as a make up for the days in which he corrupted on purpose, as narrated by al-baihaqī with a jayyid (excellent) chain, and similarly narrated by Abū Daūd. Further, since it is compulsory to make qadhā’ for the one who left the prayer in forgetfulness, then the one who left it on purpose is of greater reason.