He has specified hearing, sight, and hearts, because the religious and worldly benefits that relate to them are greater than those that relate to others. The primary benefit of them is that they use their hearing and sight in the signs of Allah and His actions, then they reflect and deduce with their hearts. Whoever does not use them for what they were created for is like one who lacks them, as Allah, the Most High, said: 'Their hearing, sight, and hearts did not avail them in anything when they were denying the signs of Allah.' The primary gratitude for the blessing in them is the acknowledgment of the One who bestowed it, and that one does not make for Him a rival or partner, meaning: you give thanks with little gratitude. And 'what' is added for emphasis, meaning truly, He created you and spread you through reproduction, and to Him you will be gathered on the Day of Resurrection after your dispersal. And to Him belongs the alternation of night and day, meaning He is exclusively responsible for it and He manages it; no one else can control them. It was also read: 'they understand,' with a 'ya' from Abu Amr.