The Prophet ﷺ was asked which prayer is best. He replied, "The one with the longest standing."
حدثنا بكر بن خلف أبو بشر حدثنا أبو عاصم عن ابن جريج عن أبي الزبير
سئل النبي ﷺ أي الصلاة أفضل قال طول القنوت
Muslim narrated it in the chapter "The Prayer of the Traveler," in the section "The Best Prayer Is the One with the Longest Standing," hadith no. 756, from the hadith of Abu Asim, through this same chain.