Say: "Indeed, the death from which you flee," meaning: that which you dislike, "will surely meet you. Then you will be returned," on the Day of Resurrection, "to the Knower of the unseen and the witnessed." The unseen is what is hidden, and the witnessed is what is open/evident.
﴿قُلْ إِنَّ الْمَوْتَ الَّذِي تَفِرُّونَ مِنْهُ﴾ يَعْنِي: تكرهونه ﴿فَإِنَّهُ مُلاقِيكُمْ ثُمَّ تردون﴾ يَوْم الْقِيَامَة ﴿إِلَى عَالِمِ الْغَيْبِ وَالشَّهَادَة﴾ الْغَيْب: السِّرّ، وَالشَّهَادَة: الْعَلَانِيَة.