According to the scripture that was given, the harps are indeed scriptural. Go read.

William Cowper suffered from deep depression for most of his life. In 1764 he found himself within the walls of an institution for the mentally ill. There in the asylum, William Cowper found Christ through reading the Bible.

Despite his emotional pain, or perhaps because of it, Cowper produced literature of amazing insight. He is still renowned in literary circles as on of England's greatest poets.

This hymn written about 1770 is based on Zechariah 13:1. - Great Songs of Faith by Brown and Norton

The original 5th verse is the same words, but reverse order of sentences:

Then in a nobler, sweeter song,

I'll sing Thy pow'r to save,

When this poor lisping, stammering tongue

Lies silent in the grave,

Lies silent in the grave,

Lies silent in the grave;

When this poor lisping, stammering tongue

Lies silent in the grave.

The beginning of the original 5th verse connected very well to the end of verse 4. This was followed by a final 6th verse:

Lord, I believe Thou hast prepared,

unworthy though I be,

For me a blood-bought free reward,

a golden harp for me!

’Tis strung and tuned for endless years,

and formed by power divine,

To sound in God the Father’s ears

no other name but Thine.

Many evangelicals probably do not like the 6th verse because of the "golden harp". Without the 6th verse, the original 5th verse would end the song with "lies silent in the grave". Not an uplifting way to end. So the sentence order in the 5th verse was reversed.

I like the revised song, but I like the original better. The 5th verse takes you low and the final verse fills you with a special hope. I also like that the verse 6 ending does not have the repeat. It makes for variety and a fitting conclusion. Besides, the overcoming Christians are given harps (I think symbolic, which is the meaning Cowper gives it also) in Rev. 15:2; 14:2; cf. 5:8.

This song has so much power in the words. United together in song across the nations singing one Name!! King of kings and Lord of lords.

Redeeming love has been my theme and shall be till I die...It's so awesome to follow the Lord.

The lyrics presented here in verse five do appear to be the ones that William Cowper published, according to several sources that I researched. Note: There are some publications that make a small change in verse four, with the first line starting as: "For since by faith..." rather than "E'er since by faith.."

There is also an additional verse, sometimes used, which is perhaps better forgotten, as it cites acquiring "a golden harp." Such an unscriptural verse detracts from the sentiment of the song. As published here, it seems to encapsulate the experience of a "saved one:"

Verse one: seeing our guilt; Verse two: being washed; Verse three: salvation; Verse four: Faith; Verse Five: Eternity!

As a child, I remember singing the last verse of this song differently. I remember seeing it different in the old hymnals. "Then in a nobler, sweeter song, I'll sing Thy power to save, when this poor lisping, stammering tongue lies silent in the grave. Which is correct???

This song builds my faith and encourages me.

Jesus change my life! I sing forever this Name!

very absolute hymn to hear for all the non-believers. Even though I am a sinner the fountain of blood cleanse me. Amen!!!

Such a cool arrangement for an old Hymn!