Derasha 33 on Beshalach 15:2

English: Rabbi Yose HaGelili expounded: How did they recite the song? An infant lying on his mother’s knees and a suckling nursing at his mother’s breasts — as soon as they saw the Shechinah the infant raised his neck and the suckling released the breast from his mouth and they said “This is my God,” as it is stated “From the mouth of infants and sucklings You have established strength.”