Matthew 6:7

But when ye pray, use not vain repetitions, as the heathens do, for they think they shall be heard for their speaking much:

Romans 1:21

so that they are inexcusable; because having thus known God they glorified Him not as God, neither were they thankful; but were infatuated by their own reasonings, and their heart being void of understanding was darkened.

1 Peter 1:18

knowing that ye were redeemed from your vain conversation learned by tradition from your fathers, not with corruptible things, as silver and gold;

Treasury of Scripture Knowledge

Summary

For the customs of the people are vain: for one cutteth a tree out of the forest, the work of the hands of the workman, with the axe.

General references

Bible References

Customs

Matthew 6:7
But when ye pray, use not vain repetitions, as the heathens do, for they think they shall be heard for their speaking much:
Romans 1:21
so that they are inexcusable; because having thus known God they glorified Him not as God, neither were they thankful; but were infatuated by their own reasonings, and their heart being void of understanding was darkened.
1 Peter 1:18
knowing that ye were redeemed from your vain conversation learned by tradition from your fathers, not with corruptible things, as silver and gold;

General references

Acts 16:21
which it is not lawful for us to receive, nor practise, who are Romans.