Tafsir of Al-Mu'minoon 23:78

He is the One who originated for you hearing and sight, so that you may perceive through them the signs—both those sent down [by revelation] and those manifest in creation.

And hearts, that you may contemplate the signs through them and use them to deduce evidence, in addition to other benefits. Hearing is mentioned first due to the abundance of its benefits. It is singular because it is originally an infinitive (masdar), and the eloquent speakers mostly do not make it plural. It is also said: It is singular because it perceives only one type of object, which is sound, unlike sight, which perceives lights, colors, states, and shapes; and unlike the heart, which perceives various types of conceptualizations and judgments. In the verse, there is an indication of both sensory and rational evidence. The precedence of that which indicates the former has already been mentioned, so recall it; for in [the nature of] the covenant, there is no [concept of] seniority.

That is, you offer very little thanks for these magnificent blessings. The foundation of gratitude is to employ these faculties—which are themselves dazzling blessings—for the purpose for which they were created. Thus, qalīlan (little) is in the accusative case as an attribute of an omitted infinitive. The "littleness" is understood in its literal sense, based on the address being directed toward mankind by prioritizing the believers. It is permitted that it carries the meaning of negation, based on the address being directed toward the polytheists by way of iltifāt (shifting of person). It is said: It is specifically for the believers, but this is not sound. In my view, it is better that it pertains specifically to the polytheists, with the possibility that the "littleness" is literal, as is not hidden from one who contemplates. The word mā (in mā tashkurūn), according to all opinions, is an augmentative particle for emphasis.