Is everything the Messenger of Allah, peace and blessings be upon him, commanded an obligation (fard), and how can we reconcile this with his saying: "What I have forbidden for you, avoid; and what I have commanded you to do, do of it as much as you are able"? And why is growing the beard an obligation (fard) and not a Sunnah if not every command of his is an obligation?

The sacred commands are divided into three types: First, those accompanied by indicators signifying their obligation, such as the command to pray. Second, those accompanied by indicators signifying their non-obligation, such as the saying of the Prophet (peace be upon him), "Pray before the Maghrib prayer," and then he said, "for whoever wishes." Third, the absolute command devoid of indicators, which signifies obligation according to the majority of scholars. They substantiated this with evidence from the Quran, including: the verse from Al-Ahzab, "And it is not for a believing man or a believing woman, when Allah and His Messenger have decided a matter, that they should [thereafter] have any choice about their affair"; and the verse from An-Nur, "So let those beware who dissent from his order, lest fitnah strike them or there come upon them a painful punishment"; and Allah's saying to Iblees, "What prevented you from prostrating when I commanded you?" And evidence from the Sunnah, including: the saying of Barirah (may Allah be pleased with her) to the Prophet (peace be upon him), "Are you commanding me to do so?" when he interceded for her concerning her husband; and his (peace be upon him) saying, "Were it not that I would overburden my nation, I would have commanded them to use the miswak." This does not contradict the hadith, "When I command you to do something, do of it as much as you can"; because this is a restriction on obeying the command by capability, which does not negate obligation. Accordingly, the Prophet's (peace be upon him) command to let the beard grow and lengthen it signifies obligation, due to the absence of any indicator diverting it from that meaning.