Sharon, You have most likely have found the words to the song by now , but just in case you are still searching, I will share what I found.

When I See the Blood by John G. Foote

Christ our Redeemer died on the cross,
Died for the sinner, paid all his due;
All who receive Him need never fear,
Yes, He will pass, will pass over you.
Refrain:
When I see the blood, when I see the blood,
When I see the blood, I will pass, I will pass over you.
Chiefest of sinners, Jesus will save;
As He has promised, so He will do;
Oh, sinner, hear Him, trust in His Word,
Then He will pass, will pass over you.
Judgment is coming, all will be there.
Who have rejected, who have refused?
Oh, sinner, hasten, let Jesus in,
Oh, He will pass, will pass over you.
O great compassion! O boundless love!
Jesus hath power, Jesus is true;
All who believe are safe from the storm,
Oh, He will pass, will pass over you.

Here is a link to the website
http://library.timelesstruths.org/music/When_I_See_the_Blood/

May the Lord Jesus bless you!

more words to song im looking for are "the lord said onto Moses take onto the a lamb, for im am Jehovah,i am that i am, you shall be saved if you harken unto me, when i see the blood i"ll pass over thee