Quran 38:81 from Surah Saad on Divine Marvels.
إِلَىٰ يَوۡمِ ٱلۡوَقۡتِ ٱلۡمَعۡلُومِ
English translation: Until (the) Day (of) the time well-known
Transliteration: ila yawmi al-waqti al-ma'lumi