Matthew 23:27. Ye are like unto whited sepulchers, which indeed appear beautiful outward, but are within full of dead men’s bones, and of all uncleanness.
The tombs were whitened with lime, so that they could be easily distinguished, and thus prevent the Jews from being ceremonially defiled by approaching them. See Numbers 19:18. This whitewash became soiled and washed off by the rains, and it was therefore necessary to renew it at intervals. This was usually done in the middle of the month Adar, when the streets and sewers were mended.
It is still customary in Palestine to whitewash the tombs. Mohammedans, as well as Jews, are very particular about this. See engraving on the opposite page.