Ye are like clear but bitter water, which to outward seeming is crystal pure — Bahá’u’lláh
O Ye Seeming Fair Yet Inwardly Foul! Ye are like clear but bitter water, which to outward seeming is crystal pure but of which, when tested by the divine Assayer, not a drop is accepted. Yea, the sunbeam falleth alike upon the dust and the mirror, yet differ they in reflection even as doth the star from the earth: nay, immeasurable is the difference!

Bahá’u’lláh

The Hidden Words, Part Two (Persian), No. 25

Bahá’í Reference Library