Crossing by the Measure of One's Light

Elders have long taught children of the Ṣirāṭ, the bridge laid over Jahannam, said to be thinner than a hair and sharper than a blade — a description that might make a child wonder how anyone is meant to cross it at all. The answer given is that one's passage over the Ṣirāṭ depends on the measure of light carried. Some believers will have so much light — every hair of them shining with nūr — that Jahannam itself will cry out from beneath, "quick, believer, hurry, your light is about to put out my fire." Some cross as though flying; some like a swift horse or camel. The worst case is the believer whose light sits on a single toe, like a broken torch that flickers on and off: he takes one step only when the light shows, for a wrong step taken in the dark would carry him into Jahannam, and so he stops and waits, and his crossing takes thousands of years, while the angels below reach up with hooks to catch him and the fire scorches at his skin from time to time.

It is said that a person who repeats lā ilāha illallāh a hundred times in a day will be given, on the Day of Judgment, a light upon his face so radiant that people will ask him why he glows so brightly, and he will answer only that he used to say this dhikr often — and the sole person with a greater light than his will be the one who made even more of it.