The Wisdom of Israel, by Edwin Collins, [1910], at sacred-texts.com
THE CHILD WHO QUESTIONED THOUGH CARRIED BY HIS FATHER.
Commenting on Exod. xvii. 7, "Is the Lord among us or not?" our sages say that for this want of faith the Israelites were brought in contact
with their enemy Amelek. This matter may be likened to the parable of a child who is riding on his father's shoulders, and on meeting a friend of his father's, calls out: "Have you seen my father anywhere?" Then his father sayeth unto him: "Thou art riding on my shoulders, and thou askest questions about me. I will put thee down for a moment in the presence of the enemy, so as to teach thee what my absence would mean."
Shemoth Rabbah, Chap. XXVI.