It once happened that one of the water drinkers (the descendants of Rechav, viz. Jeremiah 35:6) sacrificed an offering and a Heavenly voice issued forth from the holy of holies, saying: "He who accepted your sacrifices in the desert, He will accept your sacrifices at this time!"
It Once Happened That One of the Water Drinkers
Mekhilta Tractate Amalek 4:29