photo from here
"I will rejoice and be glad in Thy mercy:
for Thou hast considered my trouble;
Thou hast known my soul in adversities;
and hast not shut me up into the hand of the enemy:
Thou hast set my feet in a large room. ( Psalm 31 )
David exults here in a God of magnanimity -- a God who not only delivers him out of the darkness of adversity, but goes far beyond mere rescue to establish David in a space of remarkable expanse and liberality. God gave David exactly what he needed, and then far more.
"Sabbath rest means coming before the Lord in stillness,
in a turning away from exertion and anxiety,
so we can consecrate a space in time "to rejoice and be glad in Thy mercy."
It makes sense to me, in this context, that worship is the only true source of leisure --
for if we do not cast our cares upon Him, if we do not trust in His finished work,
we can never be truly at rest. Worship is indeed what allows us to have leisure in our souls, for the purpose of glorifying and enjoying fellowship with God."
From Lynn Bruce of Ambleside Online.