The Messenger of Allah ﷺ as saying: None of you should walk with one sandal, but should wear a pair or should put off both of them. (Using translation from Abū Dāʾūd 4136)
أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ «لَا يَمْشِ أَحَدُكُمْ فِي نَعْلٍ وَاحِدَةٍ لِيَنْعَلْهُمَا جَمِيعًا أَوْ لِيَخْلَعْهُمَا جَمِيعًا»