Midrash Rabbah Vayishlach, chap. 78.
A philosopher once posed Rabbi Eliezer with the question, "Does not the prophet say (Mal. i. 4), 'They shall build, but I will throw down'? and do not buildings still exist?" To which the Rabbi answered, "The prophet does not speak of buildings, but of the schemes of designers. Ye all think to contrive and build up devices, to destroy and make an end of us, but He bringeth your counsels to nought. He throweth them down, so that your devices against us have no effect." "By thy life," said the philosopher, "it is even so; we meet annually for the purpose of compassing your ruin, but a certain old man comes and upsets all your projects" (namely, Elijah).
Yalkut Malachi.
When Israel came out of Egypt, Samael rose to accuse them, and thus he spoke: "Lord of the Universe! these have till now worshiped idols, and art Thou going to divide the sea for such as they?" What did the Holy One—blessed be He!—then do? Job, one of Pharaoh's high counselors, of whom it is written (Job i. 1), "That man was perfect and upright," He took and delivered to Samael, saying, as He did so, "Behold, he is in thy hand; do with him as thou pleasest." God thought to divert his evil designs by keeping him thus occupied with Job, that Israel meanwhile might cross the sea without any hindrance, after which He would return and rescue Job from his tender mercies. God then said to Moses, "Behold I have delivered Job to Satan; make haste. Speak unto the children of Israel that they go forward" (Exod. xiv. 15).
Midrash Rabbah Shemoth, chap. 21.
No man ever received a mite (in charity) from Job, and needed to receive such a second time (because of the good-luck it brought along with it).
Ibid.
A superstitious belief prevails to some extent in Poland, among the Christian population as well as the Jews, that coins obtained in certain circumstances bring luck apart altogether from any virtue they may be supposed to convey from the giver. A penny obtained, for instance, the first thing in the morning, by stumbling on it in the street, by the sale of an article in the market, or by gift of charity, is considered to bode luck, and cherished as a pledge of good fortune by being slightly spat upon several times on receipt, and then carefully stowed away, for a longer or shorter period, in some safe sanctum. Job was the luckiest man that ever lived; his very goats even were so lucky as to kill the wolves that came to devour them; and a beggar, as we see, who received a mite from his hands, never needed afterward to beg an alms from him again. (See "Genesis according to the Talmud," p. 288, No. 16.)
"And Saul said unto the Kenites, Go, depart, etc.; for ye showed kindness to all the children of Israel" (1 Sam. xv. 6). And did they show kindness to all the children of Israel? No; but what is written is to teach that he who receives a disciple of the wise as a guest into his house, and gives him to eat and to drink, is as if he had shown kindness to all the children of Israel.
Midrash Sh'muel, chap. 18.