How can the hadith, "If the world were worth a gnat's wing to Allah, He would not give a disbeliever a single sip of water from it," which indicates the insignificance of the world, be reconciled with Allah Almighty considering some of the servants' deeds (good and evil) to be mighty, even though these deeds occur in this world?

The worldly life holds no value with Allah when compared to the Hereafter. The Messenger of Allah, peace and blessings be upon him, likened this world to the wing of a gnat, and he gave an example of it as a dead kid that is worth nothing, and also as a finger dipped in the sea. The Qur’an described this world as meager, and that the Hereafter is better and more enduring. As for what Allah described as great from the worldly enjoyments, such as the dominion of the family of Abraham, it is great in a way that befits the dominion of the people of this world, not in a way that befits the bliss of the Hereafter. As for Allah's considering people's actions, such as polytheism or slander, as grave, their gravity stems from the audacity to violate Allah's sacred limits and the immense consequences they bear in the Hereafter.