Radak

For Thou wilt not leave my soul to Sheol: Neither wilt Thou suffer Thine holy one to see the pit: – For I know that while I hold fast to life, that is the right way that I am in – and this is what he means in saying Thy holy one – I know that Thou wilt not leave my soul to go down to Sheol with the body, but wilt raise it to Thy glory. And in the Haggadic interpretation (Shoher Tob) (the explanation is given): “Everyone who hears himself reviled and holds his peace, in judgment is called ‘holy one.’” Thou wilt not suffer: a repetition of the thought with a change of words.