Untied and Retied at Every Watch of the Day

The kusti is not simply worn; it is worked. At the start of each of the five gahs, the watches into which the Zoroastrian religious day is divided, a practicing Zoroastrian performs the Padyab Kusti, a short purification followed by untying and retying the cord while reciting fixed prayers, so the garment is retied as many as five times between dawn and the following dawn. The retying itself carries meaning distinct from the wearing: the untying is understood as casting off the influence of the Hostile Spirit, and the retying as a renewed personal affirmation of the Zoroastrian creed, with specific knots corresponding to specific declarations recited aloud or silently. This makes the kusti one of very few sacred garments anywhere that is ritually manipulated on a fixed daily schedule rather than simply put on once and left.

Investiture with the kusti happens at the Navjote alongside the sudreh, and the two are treated as a single institution in practice even though they are physically separate objects, since neither is considered complete without the other once a person has been invested. Some households mark a child's growth toward the Navjote by having them practice tying a kusti months in advance, so the movements are already familiar by the day of investiture, though this preparatory custom is domestic rather than prescribed by any single authoritative text.