Hebrews 9:22
AMP - 22 [In fact] under the Law almost everything is purified by means of blood, and without the shedding of blood there is neither release from sin and its guilt nor the remission of the due and merited punishment for sins.
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It is interesting to note that the phrase "washed in the blood" is actually words from a song and not scripture. The nearest scripture comes to it is in Revelation 7:14 when it refers to the clothes that are washed in the blood of the lamb and made white. Hebrews talks about bodies being washed with pure water. Hebs 10:22.
We do well to make sure our theology is based in scripture and not song lyrics.
Shalom