«مَا يِعْجِبُه الْعَجَبْ وَلَا الصِّيَامْ فِي رَجَبْ»

The saying sketches a person who cannot be satisfied. Here al-ʿajab means a marvel, an admirable thing, rather than the feeling of astonishment: show them something remarkable and they shrug. Offer something widely regarded as good, even a pious act done freely, and they still object. The fault lies in their temperament, not in what is offered.

Fasting in Rajab, a month of the Islamic calendar, is the deliberate extreme. Many regard voluntary fasting then as meritorious, so disliking even that shows dissatisfaction beyond reason. The rhyme of ʿajab with Rajab gives the line its punch. It works as teasing mockery or exasperated complaint about someone perpetually picky or contrary.

Use this teasingly or critically about someone who rejects every offer and finds fault with everything, including choices most people would praise. It suits complaints about a fussy relative, guest or colleague. It sounds mocking rather than gentle, so take care using it about someone present.