SB 10.82.34

kṛṣṇa-rāmau pariṣvajya
 pitarāv abhivādya ca
na kiñcanocatuḥ premṇā
 sāśru-kaṇṭhau kurūdvaha
kṛṣṇa-rāmau — Kṛṣṇa and Balarāma; pariṣvajya — embracing; pitarau — Their parents; abhivādya — offering respects; ca — and; na kiñcana — nothing; ūcatuḥ — said; premṇā — with love; sa-aśru — full of tears; kaṇṭhau — whose throats; kuru-udvaha — O most heroic of the Kurus.
O hero of the Kurus, Kṛṣṇa and Balarāma embraced Their foster parents and bowed down to them, but Their throats were so choked up with tears of love that the two Lords could say nothing.

After a long separation, a respectful child should first offer obeisances to his parents. Nanda and Yaśodā gave their sons no opportunity for this, however, for as soon as they saw Them they embraced Them. Only then could Kṛṣṇa and Balarāma offer Their proper respects.