I am sure you know the word ruthless, but it derives from the now mostly defunct word ruth, meaning compassion. Upon reminding of this, I birthed a verse:
Thine eyes of ruth
Have never left me -
I may not doubt it:
They pierce all penury
And sow smiles in woes.
It was 1374 when Chaucer wrote:
'If therewith-al in you ther be no routhe, Than is it harm ye liven.'
More recently Walt Whitman told us:
'And whoever walks a furlong without sympathy, walks to his own funeral, drest in his shroud.'
How ruthful then the advice of Sri Chinmoy:
'Be kind, be all sympathy,
For each and every human being
Is forced to fight against himself.'