Is a Muslim rewarded for the remembrance of Allah—such as tahlil (saying "La ilaha illa Allah") and istighfar (seeking forgiveness)—verbally without the presence of the heart, and does he receive the full reward as stated in the hadiths about adhkar?

A Muslim should perfect their dhikr (remembrance of God) to reap its fruits, by ensuring that the remembrance is both with the tongue and the heart, because the fruits of dhikr, such as awe and increased faith, are only achieved through contemplation. For the remembrance of the heart yields knowledge and love, and instills mindfulness, whereas remembrance with the tongue alone does not achieve all these fruits. However, if a Muslim limits their dhikr to the tongue, they will still be rewarded for it, even though remembrance with the tongue alone is the weakest form of dhikr, it still holds great merit. Therefore, dhikr with both the heart and the tongue is the most complete, followed by dhikr with the heart only, then dhikr with the tongue only, and finally, the absence of both, which is the state of the losers.