Marriage is the legally or formally recognized union of two people as partners in a personal relationship (historically and in some jurisdictions specifically a union between a man and a woman).
In Islam, marriage is very important aspect of the religion, an highly rewarding act which abandoning it without any genuine reason is totally forbidden. A commandment from Allah, as established in several verses of the Quran, and supported by various hadith.
وَأَنكِحُوا۟ ٱلْأَيَٰمَىٰ مِنكُمْ وَٱلصَّٰلِحِينَ مِنْ عِبَادِكُمْ وَإِمَآئِكُمْۚ إِن يَكُونُوا۟ فُقَرَآءَ يُغْنِهِمُ ٱللَّهُ مِن فَضْلِهِۦۗ وَٱللَّهُ وَٰسِعٌ عَلِيمٌ
And marry the unmarried among you and the righteous among your male slaves and female slaves. If they should be poor, Allah will enrich them from His bounty, and Allah is all-Encompassing and Knowing.
حَدَّثَنَا عُمَرُ بْنُ حَفْصِ بْنِ غِيَاثٍ، حَدَّثَنَا أَبِي، حَدَّثَنَا الأَعْمَشُ، قَالَ حَدَّثَنِي عُمَارَةُ، عَنْ عَبْدِ الرَّحْمَنِ بْنِ يَزِيدَ، قَالَ دَخَلْتُ مَعَ عَلْقَمَةَ وَالأَسْوَدِ عَلَى عَبْدِ اللَّهِ فَقَالَ عَبْدُ اللَّهِ كُنَّا مَعَ النَّبِيِّ صلى الله عليه وسلم شَبَابًا لاَ نَجِدُ شَيْئًا فَقَالَ لَنَا رَسُولُ اللَّهُ صلى الله عليه وسلم ” يَا مَعْشَرَ الشَّبَابِ مَنِ اسْتَطَاعَ الْبَاءَةَ فَلْيَتَزَوَّجْ، فَإِنَّهُ أَغَضُّ لِلْبَصَرِ، وَأَحْصَنُ لِلْفَرْجِ، وَمَنْ لَمْ يَسْتَطِعْ فَعَلَيْهِ بِالصَّوْمِ، فَإِنَّهُ لَهُ وِجَاءٌ ”
Narrated By `Abdullah : We were with the Prophet (PBUH) while we were young and had no wealth whatever. So Allah`s Apostle said, “O young people! Whoever among you can marry, should marry, because it helps him lower his gaze and guard his modesty (i.e. his private parts from committing illegal sexual intercourse etc.), and whoever is not able to marry, should fast, as fasting diminishes his sexual power.”
Having established that marriage is a spiritual duty that must be fulfilled. Like other aspects of Islam, Marriage has principles and guidelines that is to be followed. Allah has given us the direct command on how many wives a Muslim can marry, and obligations that must be fulfilled before the marriage contract can be sealed. Allah said in the Quran
وَإِنْ خِفْتُمْ أَلَّا تُقْسِطُوا۟ فِى ٱلْيَتَٰمَىٰ فَٱنكِحُوا۟ مَا طَابَ لَكُم مِّنَ ٱلنِّسَآءِ مَثْنَىٰ وَثُلَٰثَ وَرُبَٰعَۖ فَإِنْ خِفْتُمْ أَلَّا تَعْدِلُوا۟ فَوَٰحِدَةً أَوْ مَا مَلَكَتْ أَيْمَٰنُكُمْۚ ذَٰلِكَ أَدْنَىٰٓ أَلَّا تَعُولُوا۟
And if you fear that you will not deal justly with the orphan girls, then marry those that please you of [other] women, two or three or four. But if you fear that you will not be just, then [marry only] one or those your right hand possesses. That is more suitable that you may not incline [to injustice].
Almighty Allah (SWT) has also commanded believing men to marry believing women whom they can afford to cater for and perform binding obligations according to how Allah has enriched them.
وَمَن لَّمْ يَسْتَطِعْ مِنكُمْ طَوْلًا أَن يَنكِحَ ٱلْمُحْصَنَٰتِ ٱلْمُؤْمِنَٰتِ فَمِن مَّا مَلَكَتْ أَيْمَٰنُكُم مِّن فَتَيَٰتِكُمُ ٱلْمُؤْمِنَٰتِۚ وَٱللَّهُ أَعْلَمُ بِإِيمَٰنِكُمۚ بَعْضُكُم مِّنۢ بَعْضٍۚ فَٱنكِحُوهُنَّ بِإِذْنِ أَهْلِهِنَّ وَءَاتُوهُنَّ أُجُورَهُنَّ بِٱلْمَعْرُوفِ مُحْصَنَٰتٍ غَيْرَ مُسَٰفِحَٰتٍ وَلَا مُتَّخِذَٰتِ أَخْدَانٍۚ فَإِذَآ أُحْصِنَّ فَإِنْ أَتَيْنَ بِفَٰحِشَةٍ فَعَلَيْهِنَّ نِصْفُ مَا عَلَى ٱلْمُحْصَنَٰتِ مِنَ ٱلْعَذَابِۚ ذَٰلِكَ لِمَنْ خَشِىَ ٱلْعَنَتَ مِنكُمْۚ وَأَن تَصْبِرُوا۟ خَيْرٌ لَّكُمْۗ وَٱللَّهُ غَفُورٌ رَّحِيمٌ
And whoever among you cannot [find] the means to marry free, believing women, then [he may marry] from those whom your right hands possess of believing slave girls. And Allah is most knowing about your faith. You [believers] are of one another. So marry them with the permission of their people and give them their due compensation according to what is acceptable. [They should be] chaste, neither [of] those who commit unlawful intercourse randomly nor those who take [secret] lovers. But once they are sheltered in marriage, if they should commit adultery, then for them is half the punishment for free [unmarried] women. This [allowance] is for him among you who fears sin, but to be patient is better for you. And Allah is Forgiving and Merciful.