SB 11.27.22
padyarghyacamaniyartham
trini patrani desikah
hrda sirsnatha sikhaya
gayatrya cabhimantrayet
Translation:
The worshiper should then purify those three vessels. He should sanctify the vessel holding water for washing the Lord’s feet by chanting hrdayaya namah, the vessel containing water for arghya by chanting sirase svaha, and the vessel containing water for washing the Lord’s mouth by chanting sikhayai vasat. Also, the Gayatri mantra should be chanted for all three vessels.