The renowned Hadith scholar of the last century, ‘Allamah Shaykh ‘Abd al-Fattah Abu Ghuddah (rahimahullah) wrote the following regarding Dar al-‘Ulum Deoband: 

“The great madrasah of Deoband is [like] a radiant sun that has illuminated various parts of India. It revived the Prophetic way (sunnah) academically, practically and in terms of suluk, and it removed the darkness of innovation (bid’ah), which had amassed in those lands for a lengthy time. It stripped the pools of knowledge and shari’ah from all that was alien to them in the same way that it stripped the suluk of the Sufis from new customs — such as sama’ and stringed instruments and their like from the gatherings of bid’ ah that were prevalent in India in those days. It replaced those innovations with clear and radiant sunnah — in terms of teaching and studying, suluk and propagation — until it (the madrasah) became a powerful, great and authentic source of light from which came droves of god-fearing (rabbaniyyin) ulama, who combined the excellence of knowledge and action (‘amal), while adhering to the sunnah and eliminating bid’ah. 

Quoted in Tarajim Sittah min Fuqaha al-A’lam al-Islami (Six Biographies of Jurists of the Islamic World) by Shaykh Abd al-Fattah Abu Ghuddah, page 15, published in Dirasah Hadithiyyah Fiqhiyyah ‘an Ma’arif al-Sunan Sharh Sunan al-Tirmidhi by Shaykh Muhammad Yahya Bilal Manyar.