سَنَسْتَدْرِجُهُمْ مِنْ حَيْثُ لَا يَعْلَمُونَ.
Translation: We shall draw them on gradually from where they do not know.
Ḥaythu keeps its final ḍamma even after the preposition min. The following verbal clause identifies the relevant circumstance/location.
Book example: مِنْ حَيْثُ لَا يَعْلَمُونَ
From a direction/circumstance unknown to them.
Min: preposition; ḥaythu: place adverb built on ḍamma in genitive position; lā: negator; yaʿlamūna: indicative imperfect with wāw as subject.