BT Ket 43a(5) :לא שביק איניש מידי דכי מודי ביה ^לא^ מיפטר ותבע מידי דכי {{לא}} מודה ביה מיפטר‏ : a person does not abandon something for which (the defendant) is not free from liability when he makes an admission in order to advance a claim for which he would be liable when makes an admission
See the entire entry for pṭr vb. to separate