Common Misunderstandings
A common misunderstanding with this hadith is what the man means, and more importantly, what the man does not mean. The man is saying he will pray but only the obligatory prayers, give the mandatory charity (zakat), only fast during Ramadan, and make Hajj once; and it is in these actions that he will neither increase nor decrease. The man does not mean he will backbite, oppress people, abandon those who need help, and keep sinning while performing the minimum actions. He is still obligated to behave properly, fulfill his responsibilities and keep away from sinning.

Allah(swt) states:

إِن تَجْتَنِبُوا۟ كَبَآئِرَ مَا تُنْهَوْنَ عَنْهُ نُكَفِّرْ عَنكُمْ سَيِّـَٔاتِكُمْ وَنُدْخِلْكُم مُّدْخَلًا كَرِيمًا (31)

“If you avoid the great sins you have been forbidden, We shall wipe out your minor misdeeds and let you through the entrance of honor [Paradise].” (An’Nisa 4:31)

This verse indicates that major sins can prevent us from entering paradise, regardless of the actions we do. However, avoiding these sins and performing good deeds can erase the minor sins and enter us into Paradise.