Hadithcore
Mishkat al-Masabih, 4411

He reported God’s messenger as saying, “None of you should walk with one sandal, but should walk barefoot or wear a pair.” (Bukhari and Muslim.)

وَعَنْهُ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «لَا يَمْشِي أَحَدُكُمْ فِي نعلٍ واحدةٍ ليُحفيهُما جَمِيعًا أَو لينعلهما جَمِيعًا»

References1 variant
In-Book Reference
Book 22, Hadith 101