The sign that Allah wants good for someone
He put himself in the sentence as the one who distributes.
مَنْ يُرِدِ اللَّهُ بِهِ خَيْرًا يُفَقِّهْهُ فِي الدِّينِ، وَإِنَّمَا أَنَا قَاسِمٌ وَاللَّهُ يُعْطِي
Man yuridi-Llāhu bihi khayran yufaqqihhu fi-d-dīn, wa innamā anā qāsimun wa-Llāhu yuʿṭī
Whoever Allah wants good for, He gives him understanding in the religion. I am only one who distributes, and Allah is the one who gives.
Where this comes from
Not knowledge. Fiqh, which is the understanding that lets a person work out what they have not been told. And the second clause separates the hand it comes through from the source it comes from.
The full narration
Narrated Muawiya:I heard Allah's Messenger (ﷺ) saying, "If Allah wants to do good to a person, He makes him comprehend the religion. I am just a distributor, but the grant is from Allah. (And remember) that this nation (true Muslims) will keep on following Allah's teachings strictly and they will not be harmed by any one going on a different path till Allah's order (Day of Judgment) is established
Source
Ṣaḥīḥ al-Bukhārī · 71
- Agreed upon as authentic (al-Bukhārī / Muslim)