Are the means of an act of worship equal to its causes, and do the causes for an act of worship take the same ruling as the obligatory act itself, even if there are other sufficient causes, or do they not take the ruling of the obligatory act if taking only a few of them is not sufficient to perform the obligatory act?

The Usuli (legal theory) principle: "That without which an obligation cannot be fulfilled is itself obligatory" means that if an obligation cannot be achieved except by performing a certain act, then performing that act becomes obligatory. An example of this is that preserving one's life is obligatory, and therefore eating becomes obligatory. However, consuming specific foods is not obligatory unless it becomes the sole means of preserving life. In the case where clean clothes are indistinguishable from ritually impure ones, some scholars hold the view that one should pray a number of times equal to the number of impure garments plus one additional prayer, or wash one of them and pray in it. Others hold the view that one should act based on the predominant presumption after investigation and ijtihad (independent reasoning). However, that without which the obligation itself cannot be established is not obligatory, such as acquiring the quorum (nisab) for Zakat or the ability (istita'ah) for Hajj.