כִּ֤י ׀ לֹא־תַעֲזֹ֣ב נַפְשִׁ֣י לִשְׁא֑וֹל לֹֽא־תִתֵּ֥ן חֲ֝סִידְךָ֗ לִרְא֥וֹת שָֽׁחַת׃
For Thou wilt not abandon my soul to the nether-world; Neither wilt Thou suffer Thy godly one to see the pit.
Read kabbalistic (mystical) interpretation of Psalms 16:10: and classical mystical sources.