מדרש על במדבר 21:7

Because you said: Let now a little water be fetched, and wash your feet, and recline yourselves under the tree (Gen. 18:4), I will give the precept of the paschal lamb to thy descendants, as it is said: They shall fetch to them every man a lamb (Exod. 12:3). Because you said to them Let now (na), I will give your descendants the ordinance of the Passover: You shall not eat of it raw (na) (ibid., v. 20). Because you did say A little, I will drive their enemies away little by little, as it is said: By little and little I will drive them out from before you (ibid. 23:30). Inasmuch as you said water, I will give them a well in the desert, as is said: Spring up, O well (Num. 21:7). Since you said wash your feet, I will wash away all the impurity of your descendants, as it is said: When the Lord shall have washed away the filth of the daughter of Zion (Isa. 4:4). Because you did say: Recline yourselves under a tree, I will give them the precept of the sukkah, as it is written: Go forth unto the mount and fetch olive branches (Neh. 8:15). In return for your saying: I will fetch a morsel of bread, I will cause to rain bread from heaven (Exod. 16:4). And inasmuch as you offered curd and milk, I will give you curd of kine and milk of sheep (Deut. 32:14).

23 (Numb. 21:7) “Then the people came unto Moses and said, ‘We have sinned’”: [They] knew that they had spoken against Moses, so they fell prostrate before him and said (ibid., cont.), “pray unto the Lord to remove [the serpent]⁷³The use of the singular here may be suggesting to midrashic interpreter that this was the same serpent that sinned in the Garden of Eden. from us….” There was one serpent. [(Ibid., cont.) “And he prayed”: The passage serves] to make Moses' humility known to you, in that he did not hesitate to seek mercy for them. And [it is also] to make the power of repentance known to you. As soon as they said, “We have sinned,” he was immediately reconciled to them. [The passage serves] to teach you that the one who forgives should not be cruel. And so too does it say (in Gen. 20:17), “Abraham then prayed to God, and God healed [Abimelech and his wife].” And so does it say (in Job 42:10), “The Lord restored Job’s fortunes when he prayed on behalf of his friends.” And where is it shown that if one has sinned against his companion and says to him, “I have sinned,” without [the companion] forgiving him, that [the unforgiving one] is called a sinner? Where it is stated (in I Sam. 12:23), “As for me also, far be it for me to sin against the Lord by ceasing to pray on your behalf.” When? When they came and said to him, “We have sinned,” [as stated] (in I Sam. 12:10), “and [they] said, ‘We have sinned […].’” And he answered, “Far be it from me to sin.” (Numb. 21:8), “And the Lord said unto Moses, ‘Make a fiery serpent, [and put it on a pole]; then it shall come to pass that, when anyone bitten [looks at it, he shall live],” not only one bitten by a serpent, but anyone bitten, even one bitten by an adder, by a scorpion, a wild beast, or a dog. (Numb. 21:9) “So Moses made a bronze serpent and set it up by a miracle”:⁷⁴Nes. The usual rendering would read: AND SET IT UP ON A POLE (nes). However, since nes can also mean “miracle,” the midrash is understanding it in the latter sense. He tossed it into the air and it remained there.