Mudgalapurana 3.18.13

3.18.13

sarvāṅgulībhirbāhuṃ svaṃ spṛśennyāsādikarmasu |
evamācamanaṃ proktaṃ svasvaśākhoktanāmabhiḥ ||

With all the fingers he should touch his own arm in rites such as ritual placement; / thus sipping of water is proclaimed, with the names mentioned in each own Vedic branch.