Praise be to Allaah.
Firstly:
It is well known and no Muslim has any excuse for not knowing
that purification from impurity, whether minor or major, is obligatory and
is a condition of prayer being valid. Whoever prays without purifying
himself, whether deliberately or by mistake, his prayer is invalid and he
has to repeat it; if it is done deliberately then he has committed a major
sin.
Shaykh al-Islam Ibn Taymiyah (may Allaah have mercy on him)
said:
The Muslim should not
pray facing any direction other than the qiblah, or without doing wudoo’,
bowing and prostrating. Whoever does that deserves to be criticized and
punished. End quote.
Manhaaj al-Sunnah al-Nabawiyyah,
5/204
There is a stern warning issued to one who does that:
It was narrated from ‘Abd-Allaah ibn Mas’ood (may Allaah be
pleased with him) that the Prophet (peace and blessings of Allaah be
upon him) said: “It was ordered that one of the slaves of Allaah be flogged
in his grave with one hundred lashes, but he kept asking until it was
reduced to a single blow. So he was given a single blow, then his grave was
filled with fire. When he came round, he said: ‘Why did you flog me?’ It was
said to him: ‘You offered one prayer without being taahir, and you passed by
one who was being wronged and did not help him.’” Narrated by al-Tahhaawi in
Mushkil al-Athaar, 4/231; classed as hasan by al-Albaani in
al-Silsilah al-Saheehah, 2774.
Secondly:
The scholars are agreed
that whoever prays without being taahir because he believes that it is
permissible or out of disrespect is a kaafir. He should be asked to repent,
and if he repents, all well and good, otherwise he should be executed.
But if he prays without wudoo’ out of negligence, not because
he thinks it is permissible or out of disrespect, Imam Abu Haneefah (may
Allaah have mercy on him) is of the view that this is also kufr, but the
majority of scholars are of the view that he is not a kaafir, rather he has
committed a major sin.
Al-Nawawi (may Allaah have mercy on him) said:
If he knows that he is impure and that it is haraam to pray
when one is impure, then he has committed a grave sin, but he does not
become a kaafir thereby in our view, unless he regards that as permissible.
But Abu Haneefah said: He has committed kufr because of his disrespect.
Our evidence is that it is a sin so it is akin to zina and
the like. End quote.
Al-Majmoo’ (2/84); Rawdat
al-Taalibeen, 10/67
See the Hanafi view in al-Bahr al-Raa’iq, 1/302, 151;
5/132; Haashiyat Ibn ‘Aabideen, 3/719
The one who has prayed
without purifying himself has to repent and seek forgiveness, and resolve
not to do such a thing again, then he should repeat the prayer that he
offered without purifying himself. Allaah accepts the repentance of those
who repent to Him. And he does not have to enter Islam anew.
And Allaah knows best.
See also question no. 27091.