1 Thessalonians 2:9

For ye remember, brethren, our labour and toil: working night and day, that we might not burden any of you, we preached to you the gospel of God.

2 Thessalonians 3:8

Neither did we eat any man's bread for nothing, but wrought with labour and toil, night and day, that we might not burden any of you.

Treasury of Scripture Knowledge

Summary

I have seen the travail, which God hath given to the sons of men to be exercised in it.

Bible References

General references

1 Thessalonians 2:9
For ye remember, brethren, our labour and toil: working night and day, that we might not burden any of you, we preached to you the gospel of God.
2 Thessalonians 3:8
Neither did we eat any man's bread for nothing, but wrought with labour and toil, night and day, that we might not burden any of you.