“They are all alike.” (1) Thus, it is among the gravest of major sins. Shaykh al-Islam—may Allah have mercy on him—mentioned in his book Ibṭāl al-Taḥlīl (Invalidating Legalizing Stratagems) that the warnings concerning ribā are unparalleled in relation to any other sin, apart from associating partners with Allah and disbelief.

The prohibition of ribā is established by consensus. Therefore, whoever denies its prohibition while living in a Muslim environment is an apostate, because it is one of the manifest prohibitions upon which there is consensus.

However, when we say this, does it mean that the scholars have reached consensus regarding every particular case? The answer is no. There has been disagreement concerning some cases. This is similar to what we say concerning zakāh: it is obligatory by consensus, yet there is no consensus concerning every individual case. They differed regarding working camels and cattle, jewelry, and similar matters. Yet, in general, the scholars are agreed that ribā is unlawful; indeed, it is among the major sins.

Ribā is divided into two categories: ribā al-faḍl (usury of excess) and ribā al-nasī’ah (usury of deferment). Ribā al-faḍl is an excess—that is, ribā occurring through an increase, such as if I sell you two ṣāʿ measures of wheat for three ṣāʿ measures of wheat.

Ribā al-nasī’ah is when I sell you one ribā-applicable item for another ribā-applicable item while delaying possession of both, such as selling you one ṣāʿ measure of wheat for one ṣāʿ measure of barley while delaying possession. You should know that these two categories may occur independently, may be combined, or may both be absent. Thus, if I sell you ten dirhams for one dinar while delaying possession, this is ribā al-nasī’ah. And if I sell you one ṣāʿ measure of wheat