
Thiis was published without credit in The Best Loved Poems of the American People (1936) with the title "Friendship", and since that time has sometimes been misattributed http://www.geonius.com/eliot/quotes.html to Eliot; it is actually an adaptation of lines by Dinah Craik, in A Life for a Life (1859):
Oh, the comfort — the inexpressible comfort of feeling safe with a person — having neither to weigh thoughts nor measure words, but pouring them all right out, just as they are, chaff and grain together; certain that a faithful hand will take and sift them, keep what is worth keeping, and then with the breath of kindness blow the rest away.
Misattributed