فَبِأَيِّ آلَاءِ رَبِّكُمَا تُكَذِّبَانِ

This verse is repeated 31 times throughout Surah Al-Rahman, each time after mentioning different divine favors and blessings. It addresses both humans and jinn ("you two" - referring to the two conscious species), challenging them to deny any of Allah's countless blessings. The rhetorical question implies that Allah's favors are so obvious and numerous that denying them would be unreasonable. The repetition serves to emphasize the overwhelming nature of divine blessings and to encourage gratitude and recognition. This teaches that Allah's blessings are countless and undeniable, that both humans and jinn are recipients of divine favors, that regular reflection on Allah's blessings should lead to gratitude, and that denying Allah's favors is both ungrateful and illogical. The verse encourages believers to regularly count their blessings and to respond with appropriate gratitude and worship.