Srimad Bhagavatham : 6.2.22.
Slokam-22. ( Having been released from the nooses of Yamaraja’s servants, the brahmana Ajamila, now free from fear, came to his senses and immediately offered obeisances to the Viṣṇudūtas by bowing his head at their lotus feet. He was extremely pleased by their presence, for he had seen them save his life from the hands of the servants of Yamaraja. )
dvijah pasad vinirmukto gata-bhih prakrtim gatah,
vavande sirasa vishnoh kinkaran darsanotsavah.
dvijah = the brahmana (Ajamila);
pasat = from the noose;
vinirmuktah = being released;
gata-bhih = freed from fear;
prakrtim gatah = came to his senses;
vavande = offered his respectful obeisances;
sirasa = by bowing his head;
vishnoh = of Lord Vishnu;
Vaishnavas are also Vishnudutas because they carry out the orders of Krishna. Lord Krishna is very eager for all the conditioned souls rotting in this material world to surrender to Him and be saved from material pangs in this life and punishment in hellish conditions after death. A Vaishnava therefore tries to bring conditioned souls to their senses. Those who are fortunate like Ajamila are saved by the Vishnudutas, or Vaishnavas, and thus they return back home, back to Godhead.