You did not throw when you threw, but God threw: the power inside an act belongs to God
A line of the Quran, said about a handful of dust flung in a battle that landed far beyond any arm's reach. Being handed something to do while being told in advance it will change nothing can make the doing feel like play-acting. The teaching sets the weight where it sits: a person moves, and the force moving through them was never theirs to supply.
al-Balāgh: delivering the message and nothing past it
The Quran tells its messengers again and again that their job ends at delivering. Someone sent to a person who has already made up their mind carries an obvious question, which is why bother at all. Taking on responsibility for another person's answer crushes you under a weight that was never yours to carry.
Qadar: God's measuring out of what happens
Everything that comes has its measure set beforehand. Knowing ahead of time that an effort will be turned down puts a person in an odd spot, since the work still has to be done in full. Under this teaching the refusal already has its place in the arrangement, so a person can pour themselves into something they know will fail.
al-ʿAyn al-thābita: the fixed pattern of a thing in God's knowledge
Ibn Arabi taught that each thing has a shape it always had in God's knowledge, and God's giving takes that shape as it arrives. Hearing that a person's hardness is caused from above raises the worry that they were set up to fail. On this reading the same gift reaches everyone and sets like water in whatever container holds it, so a hard heart hardens along lines it already had.
Rayn: the rust that builds up on a heart
The Quran speaks of a rust that settles on the heart from what a person keeps choosing, and al-Ghazali compared the heart to a mirror that films over and stops reflecting. Hardening rarely lands all at once. Each refusal makes the next one quieter, until a person no longer sees what they are turning down.
Istidrāj: being drawn on by degrees
The Quran warns of people led further along little by little, from a direction they never suspect, while nothing appears to go wrong for them. Someone who keeps refusing and keeps coming out fine reads that as proof they were right all along. From the inside, getting away with something feels like approval, and that feeling keeps a person walking the same road.