There is a difference between testing God and asking him for something. A schoolteacher will ask her students to sit down because she desires them to learn in an orderly fashion. That same teacher will later test her students with a quiz in order to find out what the students are capable of. It is because the teacher does not know what her students are capable of that she tests them.
For the practitioner of Ignatian spirituality, it is appropriate to ask God to give us things, such as a cure for an illness, because we truly desire them. On the other hand, it is not appropriate for us to test God by asking for the same cure only in order to find out what God is capable of. God’s capabilities can be known only by faith. No amount of miracles wrought by him could ever prove his infinite majesty.
The difference between testing God and asking for something was not understood by Ahaz, the king of Judah. “I will not ask,” Ahaz said, “I will not put the Lord to the test,” “non petam, et non tentabo Dominum,” “oὐ μὴ αἰτήσω οὐδ᾿ οὐ μὴ πειράσω Κύριον” (Isaiah 7:12). Ahaz was right not to test God. Jesus, himself, warned Satan not to do so: “Thou shalt not put the Lord, thy God, to the test,” “non tentabis Dominum Deum tuum,” “oὐκ ἐκπειράσεις κύριον τὸν θεόν σου” (Matthew 4:7). But Ahaz was wrong in refusing to ask for something. Remember, it was also Jesus who said, “ask and you shall receive,” “petite, et dabitur vobis,” “αἰτεῖτε, καὶ δοθήσεται ὑμῖν” (Matthew 7:7).
Without putting the Lord, your God, to the test, it is good to ask Him frequently for what you truly desire.