Midrash su Salmi 78:11

(Exodus 14:19) "And the angel of G d, who went before the camp of Israel, etc.": R. Yehudah says: This verse is rich in allusions. An analogy: A man was walking on the road leading his son before him when robbers came to snare him, whereupon he took him and placed him behind him, when a wolf came to snatch him, whereupon he took him and placed him in front — whereupon robbers came before him and wolves behind him — whereupon he took him and placed him on his shoulders — whereupon his son was scorched by the sun — whereupon his father spread his garment over him. He hungered and he fed him; he thirsted and he gave him to drink. Thus, the Holy One Blessed be He, viz. (Hoshea 11:3) "And I pampered Ephraim, taking them on My arms, and they did not know that I had healed them." His son was scorched by the sun, whereupon He spread his garment over him, viz. (Psalms 105:39) "He spread a cloud for a cover and fire to light up the night." "He hungered and He fed him," viz. (Exodus 16:4) "I shall rain down bread for you from heaven." He thirsted and he gave him water to drink, viz. (Psalms 78:11) "And He brought forth nozlim from a rock," "nozlim" being living waters, as in (Song of Songs 4:15) "a garden spring, a well of living waters, and nozlim, etc." and (Mishlei 5:15) "Drink waters from your pit and nozlim from your well." R. Nathan asked R. Shimon b. Yochai: In all places you find "the angel of the L rd ("yod-keh-vav-keh") — (Genesis 16:7) "and an angel of the L rd found her" — (Ibid. 9) "and the angel of the L rd said to her" — (Exodus 3:2) "and an angel of the L rd appeared to him" — And here it is written "and the angel of G d (Elokim) turned." (Why is this so?) He answered: "elohim" in all places is a judge. We are hereby apprised that Israel were being judged at that time — whether to be rescued or to be destroyed with the Egyptians (for themselves having succumbed to idolatry.)