Muhammad al-Ajlani says that I saw Sayyiduna Anas bin Malik (may Allah be pleased with him) urinating in Quba. After urinating, he cleaned his private part, then performed ablution and wiped over his socks. When he entered the mosque of Quba, he offered prayer.
Hadith Referenceالسنن المأثورة / باب في البيوع / 273
Hadith Takhrijمؤطا امام مالك، الطهارة، باب ماجاء في المسح على الخفين، رقم: 44 اسناده صحيح