ENOfficial
Narrated Suraqa bin Malik (rad): Allah’s Messenger (ﷺ) educated us about lavatory (manners) that we should sit on our left foot and keep erect our right foot. .
Source: sunnah.com
Other translations
Arabic
وَعَنْ سُرَاقَةَ بْنِ مَالِكٍ - رضى الله عنه - قَالَ: { عَلَّمْنَا رَسُولُ اَللَّهِ - صلى الله عليه وسلم -فِي اَلْخَلَاءِ: " أَنَّ نَقْعُدَ عَلَى اَلْيُسْرَى, وَنَنْصِبَ اَلْيُمْنَى" } رَوَاهُ اَلْبَيْهَقِيُّ بِسَنَدٍ ضَعِيف ٍ 1 .
sunnah.com