“Shirk is of two types, major shirk which puts a person beyond the pale of Islam, and lesser shirk.”
The first type, major shirk, is “Every type of shirk which the Lawgiver described as such and which puts a person beyond the pale of his religion” – such as devoting any kind of act of worship which should be for Allaah to someone other than Allaah, such as praying to anyone other than Allaah, fasting for anyone other than Allaah or offering a sacrifice to anyone other than Allaah. It is also a form of major shirk to offer supplication (du’aa’) to anyone other than Allaah, such as calling upon the occupant of a grave or calling upon one who is absent to help one in some way in which no one is able to help except Allaah.
The second type is minor shirk, which means every kind of speech or action that Islam describes as shirk, but it does not put a person beyond the pale of Islam – such as swearing an oath by something other than Allaah, because the Prophet (peace and blessings of Allaah be upon him) said that whoever swears an oath by something other than Allaah is guilty of kufr or shirk.”
The one who swears an oath by something other than Allaah but does not believe that anyone other than Allaah has the same greatness as Allah, is a mushrik who is guilty of lesser shirk, regardless of whether the one by whom he swore is venerated by people or not. It is not permissible to swear by the Prophet (peace and blessings of Allaah be upon him), or by the president, or by the Ka’bah, or by Jibreel, because this is shirk, but it is minor shirk which does not put a person beyond the pale of Islam.
Another type of minor shirk is showing off, which means that a person does something so that people will see it, not for the sake of Allaah.
The ways in which showing off may cancel out acts of worship are either of the following:
The first is when it is applies to an act of worship from the outset, i.e., the person is not doing that action for any reason other than showing off. In this case, the action is invalid and is rejected, because of the hadeeth of Abu Hurayrah which was attributed to the Prophet (peace and blessings of Allaah be upon him), which says that Allaah said, “I am so self-sufficient that I am in no need of having an associate. Thus he who does an action for someone else’s sake as well as Mine will have that action renounced by Me to him whom he associated with Me.”
(Narrated by Muslim, Kitaab al-Zuhd, no. 2985)
The second is when the showing off happens later on during the act of worship, i.e., the action is originally for Allaah, then showing off creeps into it. This may be one of two cases:
The first is when the person resists it – this does not harm him.
For example, a man has prayed a rak’ah, then some people come along during his second rak’ah and it occurs to him to make the rukoo’ or sujood longer, or makes himself weep, and so on. If he resists that, it does not harm him, because he is striving against this idea. But if he goes along with that, then every action which stemmed from showing off is invalid, such as if he made his standing or prostration long, or he made himself weep – all of those actions will be cancelled out. But does this invalidation extend to the entire act of worship or not?
We say that either of the following must apply:
Either the end of his act of worship was connected to the beginning (with no pause); so if the end of it is invalidated then all of it is invalidated.
This is the case with the prayer – the last part of it cannot be invalidated without the first part also being invalidated, so the whole prayer is invalid.
Or if the beginning of the action is separate from the end of it, then the first part is valid but the latter part is not. Whatever came before the showing off is valid, and what came after it is not valid.
An example of that is a man who has a hundred riyals, and gives fifty of them in charity for the sake of Allaah with a sound intention, then he gives fifty in charity for the purpose of showing off. The first fifty are accepted, and the second fifty are not accepted, because the latter is separate from the former.”
Majmoo’ Fataawa wa Rasaa’il Ibn ‘Uthaymeen, and al-Qawl al-Mufeed Sharh Kitaab al-Tawheed, vol. 1, p. 114, 1st edition