BT Šab 82a(8)Ar :ולא ליטחר"ליתהר‏ : he should not strain his rectum
See the entire entry for ṭḥr vb. D to strain at stool

BT Šab 82a(8) :לא ליתיב להדיא‏ : he should not sit down (in the privy) immediately
See the entire entry for lahdəyā (?) adv. directly facing