Treasury of Scripture Knowledge
And I gave my heart to seek and search out by wisdom concerning all things that are done under heaven (this sore travail God has given to the sons of man that they be occupied in it).
For God gives to the man that is good in his sight wisdom and knowledge and joy, but to the sinner he gives travail, to gather and to heap up, that he may give to the one that is good before God. This also is vanity and vexation of spirit.
in the sweat of thy face shalt thou eat bread until thou return unto the ground; for out of it wast thou taken, for dust thou art, and unto dust shalt thou return.
1 Thessalonians 2:9
For ye remember, brethren, our labour and travail, for labouring night and day, not to be a burden unto any of you, we preached among you the gospel of God.
2 Thessalonians 3:8
neither did we eat any man's bread for nought, but working with labour and travail night and day, that we might not be a burden to any of you,