It was narrated from Aishah that: the Messenger of Allah (ﷺ) said: “Marriage is part of my sunnah, and whoever does not follow my sunnah has nothing to do with me. Get married, for I will boast of your great numbers before the nations. Whoever has the means, let him get married, and whoever does not, then he should fast for it will diminish his desire.”
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا أَحْمَدُ بْنُ الأَزْهَرِ، حَدَّثَنَا آدَمُ، حَدَّثَنَا عِيسَى بْنُ مَيْمُونٍ، عَنِ الْقَاسِمِ، عَنْ عَائِشَةَ، قَالَتْ قَالَ رَسُولُ اللَّهِ ـ صلى الله عليه وسلم ـ " النِّكَاحُ مِنْ سُنَّتِي فَمَنْ لَمْ يَعْمَلْ بِسُنَّتِي فَلَيْسَ مِنِّي وَتَزَوَّجُوا فَإِنِّي مُكَاثِرٌ بِكُمُ الأُمَمَ وَمَنْ كَانَ ذَا طَوْلٍ فَلْيَنْكِحْ وَمَنْ لَمْ يَجِدْ فَعَلَيْهِ بِالصِّيَامِ فَإِنَّ الصَّوْمَ لَهُ وِجَاءٌ " .
sunnah.com