Say, "Indeed, my Lord casts the truth," meaning: He sends down the revelation. "The Knower of the unseen," the unseen of the heaven: what descends from it of rain and other things, and the unseen of the earth: what emerges from it of vegetation and other things.
﴿قُلْ إِنَّ رَبِّي يَقْذِفُ بِالْحَقِّ﴾ أَي: ينزل الْوَحْي ﴿عَلَّامُ الْغُيُوبِ﴾ غيب السَّمَاء: مَا ينزل مِنْهَا من الْمَطَر وَغَيره، وغيب الأَرْض مَا يخرج مِنْهَا من النَّبَات وَغَيره.