A track from their third album Pour Down Like Silver, which was written shortly after they had converted to the Sufi strand of Islam.

The Wikipedia entry for Pour Down Like Silver talks about the effect this had on their music.

It says of Dimming of the Day:

The understated and elegant "Dimming of the Day" was sung by Linda Thompson on this album, but Richard Thompson has continued to feature it in his own live shows for many years - an indication of its deep personal significance. This song is an example of Thompson writing in a centuries-old Sufic tradition of expressing divine love in earthly terms. 

On the album "Dimming of the Day" segues into a solo guitar performance of Scots composer James Scott Skinner's "Dargai" that perfectly matches the mood of the song and serves to bring the album to a contemplative conclusion.

Now listen to Richard and Linda Thompson sing A Heart Needs a Home.