the Persian: “Has your Prophet taught you even how to relieve yourselves?” He replied, “Yes.” (1) That is, the etiquettes of relieving oneself. Thus, the Sunnah contains etiquettes for relieving oneself, and the Quran contains etiquettes of sitting. Allah—Exalted is He—says: “When you are told, ‘Make room in gatherings,’ then make room.” [Surah al-Mujadilah 58:11] It also contains etiquettes of seeking permission and of entering. Allah—Exalted is He—says: “When you enter houses, greet one another with peace.” [Surah al-Nur 24:61]
So Islamic law—praise be to Allah—is comprehensive of everything. Some matters are addressed by the law specifically, while others fall under one of its general principles. Whoever says that the revealed texts do not suffice for even a tenth of what people need has certainly erred. Rather, we say that the texts suffice for everything people need; yet some matters are explicitly stated, whereas others fall under general principles, which are recognized by those whom Allah has granted knowledge and understanding.
It says in al-Rawd (2): “It is permissible by consensus, due to the saying of Allah—Exalted is He—: ‘Allah has made trade lawful.’” [Surah al-Baqarah 2:275] Some say that this wording is open to objection.
The correct wording is to say: It is permissible according to the Quran, the Sunnah, and scholarly consensus. However, the author has a particular perspective: he wished to begin with consensus and then mention its supporting evidence, because consensus is decisive in settling disagreement, unlike a textual proof. A text may be open to interpretive qualification, so the person against whom you cite it may not agree with the conclusion you draw from it. Each approach has its rationale. Whoever says, “I begin with the Quran, the Sunnah, and consensus,”