What is the ruling on the lack of devotion or contemplation during dhikr due to mind-wandering, and will the one who performs it be rewarded, and does the hadith "Indeed, Allah does not look at the supplication from a heedless heart" apply to it?

The one who performs dhikr (remembrance of Allah) should ponder over the dhikr and feel the greatness of Allah while performing it, so that both the heart and the tongue are engaged in dhikr and the reward is complete. If one performs dhikr with their tongue without contemplation, they will be rewarded for the movement of the tongue, which is better than moving the tongue with backbiting or remaining completely silent. However, the reward of the one who performs dhikr varies according to their contemplation of the dhikr or lack thereof. As for the hadith: «Supplicate to Allah with certainty of being answered, and know that Allah does not answer a supplication from a heedless, distracted heart», it pertains to the acceptance of supplication, which requires conditions in the supplicant, in the supplication, and in the thing being supplicated for, among which are sincerity of intention and presence of heart. For Allah does not answer a supplication from a heedless, distracted heart.