A surprise will always be better than a promise. You can think about it also. If someone gifts you something or surprises you, it makes you more happy than being promised which means you will have to keep waiting for what you are being promised.
And I have noticed one common thing among children. Once you promise them something, they always have it in their minds until you get it for them. What if you didn’t get it for them? It means they will feel sad and some children may even fall sick.
That’s why God never promises. Our God is a God whom is full of surprises and when He wants to do something for us, He surprises us. It’s far better than we keeping it on our minds and expecting them now and then. Do not just promise anything.
Ecclesiastes 5:4 says; When thou vowest a vow unto God, defer not to pay it; for he hath no pleasure in fools: pay that which thou hast vowed.
Better is it that thou shouldest not vow, than that thou shouldest vow and not pay.
God doesn’t even want you to promise him anything or make a promise. He isn’t like that. God wants you to surprise him as well. God wants you to do what you want to do willingly and He is going to reward you.
Then, if you can’t make promise to the God who created you, why then will you make promise to a mere human or even your child? Don’t do that. Have you ever thought about a situation where you may not be able to fulfill the promise? So, do not make any promise.
Let everything flow naturally and just continue to find a way to surprise your children and they will definitely pray for you.