1 Samuel 15:29 and Psalm 55:19
29 "Also the Glory of Israel will not lie or change His mind; for He is not a man that He should change His mind."
19 God will hear and answer them — even the one who sits enthroned from of old — Selah. With whom there is no change, and who do not fear God.
Most things or people you rely on in the natural realm are frequently changing in reaction to things around them or their feelings.
One of the best things about God is that He doesn't change. What He promises He will fulfill You can count on God to keep His word now and for generations to come. He promises eternal life to those who believe in Jesus. He promises forgiveness for sins to those who ask. He promises to lead believers in their lives in the way they should go. He promises to heal their diseases, and to answer their prayers. He promises to meet physical needs and He won't fail on these or countless other promises. Meditate on the Scripture and God will expand and strengthen your faith. He wants to bring to the place that you are calm no matter what He is doing or allowing in your life.
Remember (as Warren Weirsbe said), “living by faith means living by promises, not explanations.”