Remember Scripture, the great promise to Abraham was given freely out of the grace of God but it demanded of him the very seed of that promise, his son Isaac. Jesus gave of Himself freely, and was given by His Father – but never confuse freely with lightly. It cost God a great deal to give his one and only Son whom He loved – whose very nature was love.
To give freely concerns the will of the giver. In a free gift, the giver is neither coerced nor threatened in any way but is motivated by their own self and seek the benefit of the receiver above all. To give lightly deals with the cost to the giver. This is not to say that there is any limit or even measure to our Almighty Lord. Do not think cost in terms of how big, or what percentage of the assets it will take away. Think of cost in terms of preciousness and importance. Giving away a stuffed animal may cost you only a few dollars; but giving away the same object when it was a gift from a loved one who is now in glory is much more costly. It is in this manner which we should understand the heaviness with which our God gives.
It is plain to see why the gift of His Son would be so costly, because of the immeasurable preciousness of His child. But why not lightly with the promise of Abraham, after all He is simply mortal and God can write His heritage in any fashion without even reaching the beginnings of His power. Through understanding this we may also be able to understand why the provision we seek is often free but not light.
A question should help enlighten this subject: What is provision to God? And what is provision to man?