…Truly prayer guards against lewd acts and indecency…This verse refers to the adornment (tazyīn) that [is derived from] shunning all lewd acts and indecency, and this [is attained] through one thing, namely, sincerity (ikhlāṣ) within the prayer (ṣalāt). Every prayer that does not restrain shameful and unjust deeds, and is devoid of the adornment of shunning of these deeds, is defective, and it is incumbent upon the person [in this case] to purify it [his prayer].His words, Exalted is He: