Matthew 6:7

But when ye pray, use not vain repetitions, as the heathen do; for they think that they shall be heard for the multitude of their words.

Romans 1:21

Because though they knew God, they did not glorify him as God, nor were they thankful to him; but became perverse in their reasonings, and their senseless minds were darkened;

1 Peter 1:18

knowing that not with perishable things, silver or gold, were ye redeemed from your vain manner of life received by tradition from your fathers,

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 heathen do; for they think that they shall be heard for the multitude of their words.
Romans 1:21
Because though they knew God, they did not glorify him as God, nor were they thankful to him; but became perverse in their reasonings, and their senseless minds were darkened;
1 Peter 1:18
knowing that not with perishable things, silver or gold, were ye redeemed from your vain manner of life received by tradition from your fathers,

General references

Acts 16:21
and they teach customs which it is not lawful for us Romans to receive or observe.