Matthew 23:27

Whited sepulchres [τ α φ ο ι ς κ ε κ ο ν ι α μ ε ν ο ι ς]. Not the rock - tombs, belonging mostly to the rich, but the graves covered with plastered structures. In general, cemeteries were outside of cities; but any dead body found in the field was to be buried on the spot where it had been discovered. A pilgrim to the Passover, for instance, might easily come upon such a grave in his journey, and contract uncleanness by the contact (Numbers 19:16). It was therefore ordered that all sepulchres should be whitewashed a month before Passover, in order to make them conspicuous, so that travelers might avoid ceremonial defilement. The fact that this general whitewashing was going on at the time when Jesus administered this rebuke to the Pharisees gave point to the comparison. The word kekoniamenoiv (whitened, from koniv, dust) carries the idea of whitening with a powder, as powdered lime.