Agniveshyagrihyasutra 2.6.7.31

2.6.7.31

dadhnā havirmiśrena trivṛtānnena yathākarma hutvāthāpa ācamya amṛtāpidhānamasi ityācāntaḥ punarācamya prāṇānāṃ granthirasi sa mā visrasa iti nābhideśamabhimṛśati \

Having offered as prescribed with curd mixed with oblation-food, threefold food, and having sipped water, having sipped water with: "You are the cover of immortality," and having sipped water again, he touches the navel region with: "You are the knot of the life-breaths; do not loosen me!"