And Zacharias said to the angel, “How shall I know this? For I am an old man, and my wife is well advanced in years…” “But behold, you will be mute and not able to speak until the day these things take place, because you did not believe my words which will be fulfilled in their own time.” – Luke 1:18, 20

His fault was that he looked at the difficulty. “I am an old man,” said he, “and my wife is well stricken in years.” And while he looked at the difficulty, he would fain suggest a remedy; he wanted a sign. I have often trembled in my own soul when I have felt an inclination thus to tempt the Lord by looking for some minute circumstance to verify a magnificent promise. When I have thought, “Hereby shall I know whether He does hear prayer or not,” a cold shiver has passed over me, the shudder has gone through my soul that ever I should think of challenging the truth of God’s word, when the fact is so certain. To us who have full often cried unto the Lord in our distresses and been delivered out of our troubles, to raise such a question is indeed ungrateful. For a child of God who habitually prays to his Father in heaven to look upon His faithfulness as a matter of uncertainty is to degrade himself, and to dishonour his Lord. Yet there is no denying the tendency and disposition among us to want a sign. As we read a prophecy of the future, we crave a token in the present. If the Lord were pleased to give us a sign, or if he told us to ask for a sign, we should be quite right in attaching a high importance thereto, but for us to doubt a plain promise, and, therefore, ask a sign, is to sin against the Lord. Sometimes we have wanted signs in spiritual things. Meet and proper is it for us to rejoice in the true delights of fellowship with Christ, but it ill becomes us to make our feelings a kind of test of our acceptance, or to say, “I will not believe God if He does not indulge me with certain manifestations of grace; unless He gives me the sweetmeats I crave, I will be sulky and sullen, and refuse to eat the children’s bread.” Why, such conduct is willful and wicked; it is weak, and utterly inexcusable. Yet how many of us have been guilty of this folly? ~ C.H. Spurgeon

https://www.blueletterbible.org/Comm/spurgeon_charles/sermons/3495.cfm