Chandogya Upanishad 1.12

Now follows the udgîtha of the dogs. Vaka Dâlbhya, or, as he was also called, Glâva Maitreya, went out to repeat the Veda (in a quiet place).

A white (dog) appeared before him, and other dogs gathering round him, said to him: 'Sir, sing and get us food, we are hungry.'

The white dog said to them: 'Come to me to-morrow morning.' Vaka Dâlbhya, or, as he was also called, Glâva Maitreya, watched.

The dogs came on, holding together, each dog keeping the tail of the preceding dog in his mouth, as the priests do when they are going to sing praises with the Vahishpavamâna hymn. After they had settled down, they began to say Hin.

'Om, let us eat! Om, let us drink! Om, may the divine Varuna, Pragâpati, Savitri bring us food! Lord of food, bring hither food, bring it, Om!'