Psalm 127:1-2

If the Lord does not build a house, then those who build it work in vain. If the Lord does not guard a city, then the watchman stands guard in vain. It is vain for you to rise early, come home late, and work so hard for your food. Yes, he can provide for those whom he loves even when they sleep.

The Lord must be in all that we build, all that we work towards. If He is not in it, then it will surely fail and fall to the ground. He is the everything that matters most; the life that brings meaning, purpose, and success to any plan. There is a difference between working in Christ and "toiling". Toiling is hard, laborious, and often painful work that gains us very little. This is not the kind of work we are being told to embrace in this verse. The Lord is gracious and is even able to provide for us as we rest. It is so important that we are able to rest in the sufficiency of Jesus Christ. He delights in us, cares for us deeply, and will provide for us. Trust in the Lord, because He is the only sure thing!