Objection 1. It would seem that the temptation of God does not consist in certain deeds wherein the result is expected from the power of God alone. Just as God is tempted by man so is man tempted by God, man, and demons.
But when man is tempted the result is not always expected from his power. Therefore neither is God tempted when the result is expected from His power alone.
Objection 2. Further, all those who work miracles by invoking the divine name look for an effect due to God's power alone. Therefore, if the temptation of God consisted in such like deeds, all who work miracles would tempt God.
Objection 3. Further, it seems to belong to man's perfection that he should put aside human aids and put his hope in God alone. Hence Ambrose, commenting on Luke 9:3, "Take nothing for your journey," etc. says: "The Gospel precept points out what is required of him that announces the kingdom of God, namely, that he should not depend on worldly assistance, and that, taking assurance from his faith, he should hold himself to be the more able to provide for himself, the less he seeks these things." And the Blessed Agatha said: "I have never treated my body with bodily medicine, I have my Lord Jesus Christ, Who restores all things by His mere word." [Office of St. Agatha, eighth Responsory (Dominican Breviary).] But the temptation of God does not consist in anything pertaining to perfection. Therefore the temptation of God does not consist in such like deeds, wherein the help of God alone is expected.
On the contrary, Augustine says (Contra Faust. xxii, 36): "Christ who gave proof of God's power by teaching and reproving openly, yet not allowing the rage of His enemies to prevail against Him, nevertheless by fleeing and hiding, instructed human weakness, lest it should dare to tempt God when it has to strive to escape from that which it needs to avoid." From this it would seem that the temptation of God consists in omitting to do what one can in order to escape from danger, and relying on the assistance of God alone.
I answer that, Properly speaking, to tempt is to test the person tempted. Now we put a person to the test by words or by deeds. By words, that we may find out whether he knows what we ask, or whether he can and will grant it: by deeds, when, by what we do, we probe another's prudence, will or power. Either of these may happen in two ways. First, openly, as when one declares oneself a tempter: thus Samson (Judges 14:12) proposed a riddle to the Philistines in order to tempt them. On the second place it may be done with cunning and by stealth, as the Pharisees tempted Christ, as we read in Matthew 22:15, sqq. Again this is sometimes done explicitly, as when anyone intends, by word or deed, to put some person to the test; and sometimes implicitly, when, to wit, though he does not intend to test a person, yet that which he does or says can seemingly have no other purpose than putting him to a test.
Accordingly, man tempts God sometimes by words, sometimes by deeds. Now we speak with God in words when we pray. Hence a man tempts God explicitly in his prayers when he asks something of God with the intention of probing God's knowledge, power or will. He tempts God explicitly by deeds when he intends, by whatever he does, to experiment on God's power, good will or wisdom. But He will tempt God implicitly, if, though he does not intend to make an experiment on God, yet he asks for or does something which has no other use than to prove God's power, goodness or knowledge. Thus when a man wishes his horse to gallop in order to escape from the enemy, this is not giving the horse a trial: but if he make the horse gallop with out any useful purpose, it seems to be nothing else than a trial of the horse's speed; and the same applies to all other things. Accordingly when a man in his prayers or deeds entrusts himself to the divine assistance for some urgent or useful motive, this is not to tempt God: for it is written (2 Chronicles 20:12): "As we know not what to do, we can only turn our eyes to Thee." But if this be done without any useful or urgent motive, this is to tempt God implicitly. Wherefore a gloss on Deuteronomy 6:16, "Thou shalt not tempt the Lord thy God," says: "A man tempts God, if having the means at hand, without reason he chooses a dangerous course, trying whether he can be delivered by God."
Reply to Objection 1. Man also is sometimes tempted by means of deeds, to test his ability or knowledge or will to uphold or oppose those same deeds.
Reply to Objection 2. When saints work miracles by their prayers, they are moved by a motive of necessity or usefulness to ask for that which is an effect of the divine power.
Reply to Objection 3. The preachers of God's kingdom dispense with temporal aids, so as to be freer to give their time to the word of God: wherefore if they depend on God alone, it does not follow that they tempt God. But if they were to neglect human assistance without any useful or urgent motive, they would be tempting God. Hence Augustine (Contra Faust. xxii, 36) says that "Paul fled, not through ceasing to believe in God, but lest he should tempt God, were he not to flee when he had the means of flight." The Blessed Agatha had experience of God's kindness towards her, so that either she did not suffer such sickness as required bodily medicine, or else she felt herself suddenly cured by God.
Source: Summa Theologica (New Advent)