There are many Bible Promises like Length of Days, Peace etc. Each of them have a condition attached, and a Promise if you fulfil them. So for e.g. Proverbs 3 says this.
Proverbs 3: Wisdom Bestows Well-Being
1My son, do not forget my teaching,
but keep my commands in your heart,
2for they will prolong your life many years
and bring you peace and prosperity.
3Let love and faithfulness never leave you;
bind them around your neck,
write them on the tablet of your heart.
4Then you will win favor and a good name
in the sight of God and man.
And so, what conclusion can we deduce from this?
(1) if you faithfuly seek after Wisdom
(2) if you love God and keep His Commands.
There are many blessings promised for this such as
(1) they, these commands, will prolong your life
(2) they will bring you peace and prosperity
and so on.
And if you bind love and faithfulness around your neck, and write them in your heart,
(1) you will win favor and a good name in the sight of God and man.
Incidentally, of the Christ Child, it is said:
"And Jesus grew in wisdom and stature, and in favor with God and man." (Luk 2:52). So He Himself, who is Incarnate Wisdom, did these things, and received many blessings from His Father for them.
There are blessings promised to those who keep God's commandments. Why is this controversial? And the blessings of Abraham, which also means those promised in the OT as a whole, now come to us Christians, through Christ Jesus, as it says in many Bible passages. And as it says in 1 Jn, he who says he knows Him should walk as He walked, and then we will receive these blessings. There are many blessings, not just prosperity; there is spiritual joy, peace, contentment and more.
God Bless.