Skandapurana 16.206.15

16.206.15

saṃdhyayorubhayorjāpye bhojane daṃtadhāvane..
pitṛkārye ca daive ca tathā mūtrapurīṣayoḥ..
gurūṇāṃ saṃnidhau dāne yoge caiva viśeṣataḥ ..
eteṣu maunamātiṣṭhansvargaṃ prāpnoti mānavaḥ .. 15 ..

At both twilights, during recitation of prayers, while eating, while brushing teeth, / in ancestral rites, in divine rites, as well as while passing urine and feces, / in the presence of teachers, during giving of gifts, and especially in yoga— / observing silence in these, a person attains heaven. 15