Skandapurana 16.17.31

16.17.31

tatastu tarppayenmaṃtrānsarvāṃstāṃstu karāgrajaiḥ ..
tulanādūrdhvato devānsavyena ca munīṃstathā ..
pitṝṃścaivāpasavyena hṛdbījena pratarpayet .. 31 ..

Then one should offer water to all those mantras with the tips of the fingers: / lifting upward to the gods, with the sacred thread on the right shoulder to the sages, / and with the sacred thread on the left shoulder to the ancestors, one should offer with the heart-bīja.