Job 8:15

He shall lean upon his house - This is an allusion to the web or house of the spider. The hope of the hypocrite is called the house which he has built for himself; his home, his refuge, his support. But it shall fail him. In times of trial he will trust to it for support, and it will be found to be as frail as the web of the spider. How little the light and slender thread which a spider spins would avail a man for support in time of danger! So frail and unsubstantial will be the hope of the hypocrite! It is impossible to conceive any figure which would more strongly describe the utter vanity of the hopes of the wicked. A similar comparison occurs in the Koran, Sur. 28, 40: “They who assume any other patrons to themselves besides God, are like the spider building his house; for the house of the spider is most feeble.”

He shall hold it fast - Or, he shall lay hold on it to sustain him, denoting the avidity with which the hypocrite seizes upon his hope. The figure is still taken from the spider, and is an instance of a careful observation of the habits of that insect. The idea is, that the spider, when a high wind or a tempest blows, seizes upon its slender web to sustain itself. But it is insufficient. The wind sweeps all away. So the tempest of calamity sweeps away the hypocrite, though he grasps at his hope, and would seek security in that, as a spider does in the light and tenuous thread which it has spun.