This is mentioned in Village School, chapter 3, as a hymn that the vicar would like Miss Read to teach to the school children, however she considers it to be unsuitable for the children.
It is from the poem The Hymn by John Milton (1608 - 1674). It goes on for 28 verses, so only the relevant verse is given here.
For if such holy song
Enwrap our fancy long,
Time will run back, and fetch the age of gold,
And speckled Vanity
Will sicken soon and die,
And leprous Sin will melt from earthly mould;
And Hell itself will pass away,
And leave her dolorous mansions to the peering day.