Saydna Anas bin Malik رضیﷲ عنه reported that Rasool صلی اللہ علیہ وسلم said:
أُتِيتُ بِالْبُرَاقِ، وَهُوَ دَابَّةٌ أَبْيَضُ طَوِيلٌ فَوْقَ الْحِمَارِ، وَدُونَ الْبَغْلِ، يَضَعُ حَافِرَهُ عِنْدَ مُنْتَهَى طَرْفِهِ»، قَالَ: «فَرَكِبْتُهُ حَتَّى أَتَيْتُ بَيْتَ الْمَقْدِسِ»، قَالَ: «فَرَبَطْتُهُ بِالْحَلْقَةِ الَّتِي يَرْبِطُ بِهِ الْأَنْبِيَاءُ
I was brought al-Buraq Who is an animal white and long, larger than a donkey but smaller than a mule, who would place his hoof a distance equal to the range of version. I mounted it and came to the Temple (Bait Maqdis in Jerusalem), then tethered it to the ring used by the prophets.
[Sahih Muslim 411]
Saydna Malik bin Sa'sa reported that Rasool صلی اللہ علیہ وسلم said
ثُمَّ أُتِيتُ بِدَابَّةٍ أَبْيَضَ، يُقَالُ لَهُ: الْبُرَاقُ، فَوْقَ الْحِمَارِ، وَدُونَ الْبَغْلِ، يَقَعُ خَطْوُهُ عِنْدَ أَقْصَى طَرْفِهِ، فَحُمِلْتُ عَلَيْهِ
I was then brought a white beast which is called al-Buraq, bigger than a donkey and smaller than a mule. Its stride was as long as the eye could reach.
[Sahih Muslim 416, Sahih Bukhari 3887]
Hafiz ibn Mulaqqin رحمہ اللہ said:
مسابقه بالتواتر انه صلى الله عليه وسلم عرج به على دابة يقال له البراق.
It is proven from the Mutawatir narrations that Prophet صلی اللہ علیہ وسلم was mounted on "Burraq" named beast on the journey of Mai'raj.
[At Tawzeeh li sharah Jami'i as Sahih 5/246]
~Via Shaikh Ghulam Mustafa Zaheer