Before we can undertake any serious discussion of fiqh, it is necessary to become familiar with the way the Hanbali fuqaha define and use some words. The following definitions are taken from Sheikh `Abd Al-Qadir ibn Badran's introduction to Akhs.ar Al-Mukhtas.irt. They get a bit complicated in the end, so I have restated some of them in an alternative form.
Legal ruling - that which the legal address indicates.
Wajib (obligatory) - Its linguistic meaning is: descending [as in: the sun begins its descent after noon], firmly rooted. Its legal meaning is: that which someone is censured for unconditionally neglecting.
Ibn Hamdan says: It includes things that one is not rewarded for doing when done absentmindedly, such as obligatory upkeep, giving back an item left for safe keeping or stolen goods, and the like. And it includes things that are unlawful for which one is not rewarded for avoiding if avoided absentmindedly."
I [Ibn Badran] say: this is if one does not do the obligatory or avoid the unlawful out of compliance to the order of Allah Most High. As for when one does it out of compliance, he is rewarded because of the hadith "Actions are only according to their intentions".
Fard (prescribed) - Its linguistic meaning is portioning, influencing, requiring, and a given share. Its legal meaning is that which is established via certain evidence, or: that which does not cease [being obligatory when omitted], intentionally or absentmindedly. Imam Ahmad said that it is that which the Qur'an requires.
Works of worship that do not have a specific time from the perspective of the Legislation, such as voluntary prayers, are not said to be 'performed in their time' (ada), made up after their time (qada), or repeated ('i`adah).
If the Legislation has given them a specific time, such as the five [obligatory] prayers and Hajj:
if it is performed in legally appointed time, it is called ada (performed on time); if it is performed after the time, it is called qada (made up). There is no difference when it is delayed because of an excuse, whether able to perform it its time (such as traveling and sickness), or not able to perform it out of some hindrance, whether legal, (such as menstruation or post-partum bleeding), or rational (such as sleep) because the act of worship is obligatory even with the excuse.
As for 'i`adah (repeating), it is that which is performed a second time during its appointed time, whether or not the repetition is because of invalidity. This includes if one were to validly pray a prayer in its appointed time, and then pray it again when the iqamah for the prayer is made while being inside the mosque; this prayer is called 'repeated' according to the Hanbalis, without there being any invalidity or excuse [for repeating it].
If performing an act of worship is required from every single individual, such as the five prayers, it is called fard `ayn (individual obligation); if it is like supererogatory actions, for example: the sunna associated with Fajr, then it is called sunnat `ayn (individual sunna).
If performing the action is unconditional, such as the funeral prayer and the two `Eid prayers, it is called fard kifayah (group obligation), and if a sufficient group of people do it, it ceases [being obligatory] on the entire group. [And similarly]: sunnat al-kifaya (group sunna), like [initiating] greetings.
Haram (unlawful) - It is that which its performer is legally censured for, even if it be verbal or actions of the heart.
Our phrase "even if verbal" includes slander, backbiting, and similar things that are unlawful to say.
Our phrase "even actions of the heart" includes hypocrisy, hatred, envy, and others.
Our phrase "legally" is an allusion to [the fact] that censure is only from the Legislation, and that people's censure is of no consideration. [Note: Good and evil have no independent, 'objective' existence; nothing is 'good' or 'evil' except by the decree of Allah Most High. Killing has no intrinsic ruling, rather it varies according to its context: murder is unlawful, self-defense is lawful, and defending one's legal charges is obligatory. --musa]
Mandub (recommended) - its linguistic meaning is being invited to something of importance, taken from the word nadab, which is the invitation. Its legal meaning is: that which someone is rewarded for performing, even if verbal or an action of the heart, yet one is not punished for unconditionally neglecting it.
The phrase "that which someone is rewarded for performing"-such as sunnas and sunna prayers associated with the obligation prayers.
The phrase "even if verbal"-such as the litanies during Hajj, and the verbal sunnan during prayer.
The phrase "even if an action of the heart"-such as humility during prayer.
Mandub is [also] called:
muraghghib fihi (encouraged to do),
The highest is: sunnah, then fadilah (meritorious), and then nafila.
Makruh (disliked) - is that which someone is praised for avoiding yet is not censured for performing.
Mubah (merely permissible) - Its linguistic meaning is permitted and known. Its legal meaning is that which in and of itself is free of praise and censure.
It is [also] called [...] halal (permissible).
Sabab (cause) - Its linguistic meaning is that which is used to arrive at something else. Its legal meaning is that which in and of itself requires something else to exist when it exists, and to be absent when it is absent-and so its legal ruling is according to its existence but not because of it. [In other words: a is the cause of b if the existence or absence of a causes b to be the same.]
For example: the sun descending from its zenith is a cause for the Zuhr prayer to become obligatory, while it is possible that the sun has passed its zenith and yet the Zuhr prayer is not obligatory because of an external mater, such as: menstruation, insanity, or lack of maturity.
Shart (condition) - Its linguistic meaning is an sign [or indication]. Its legal meaning is that whose absence requires something else to be absent and whose existence in and of itself does not require something else to exist or be absent.
[In other words: a is a condition of b if the absence of a necessitates the absence of b, while the existence of a does not in an of itself necessitate the existence or absence of b.]
[An example is] purification: its absence requires the absence of the validity of prayer, yet its existence of purification does not require the absence of prayer nor its presence.
Mani` (hindrance) - It is that whose presence requires something else to be absent, yet its absence does not in and of itself require presence or absence.
[In other worse: a hinders b if the existence of a requires that b not exist, while the absence of a does not require the existence of absence of b.]
Sihhah (soundness, validity) regarding acts of worship means that whose action removes the need to do it.
Butlan and fasad (void, invalid) are synonymous phrases, each one of them being of the same meaning according to the Hanbalis and the Shafi`is, except that the Shafi`is differentiate between them in fiqh in [some] issues.
`Azima () - Its linguistic meaning is emphatically seeking [please excuse me for this --musa]. Its legal meaning is a ruling that is established by legal evidence that is free of a preponderant contingency.
Rukhsa (dispensation) - Its linguistic meaning is easiness. Its legal meaning is that which is established contrary to [other] legal evidence because of a preponderant contingency. [Its examples include]: someone in need eating unslaughtered meat, shorting prayers while traveling, and joining [prayers while traveling].