Matsya Purana 274.44

274.44

āvāhayellokapatīn krameṇa mantrairamībhiryajamānayuktaḥ .. 274.41
ehyehi sarvāmarasiddhasādhyairabhiṣṭuto vajradharo'mareśaḥ.

Afterwards the mind should be turned to the mantras sacred to them At the close of the sacrifice when the Homas are over, the preceptors should get the music played and then taking the Valis, flowers and incense in order and invoke the Lokapals—41

The following mantras should be uttered at the time of invoking the Lokapâlas, viz :—O Indra! adored by the Devas, Sâdhyas Siddhas, come O, one armed with a thunderbolt and surrounded and fanned by the nymphs, I salute you Pray guard my sacrifice Om Indrâya Namah—42