In its context
Septuagint
17:7 But blessed is the man who trusts in the Lord, and whose hope the Lord shall be.
17:8 And he shall be as a thriving tree by the waters, and he shall cast forth his root toward a moist place: he shall not fear when heat comes, and there shall be upon him shady branches: he shall not fear in a year of drought, and he shall not fail to bear fruit.
17:9 The heart is deep beyond all things, and it is the man, and who can fathom him?
17:10 I the Lord try the hearts, and prove the reins, to give to every one according to his ways, and according to the fruits of his devices.
Pre-JPS Masoretic
17:7 Blessed is the man that trusts in the LORD, and whose hope the LORD is.
17:8 For he shall be as a tree planted by the waters, and that spreads out her roots by the river, and shall not see when heat comes, but her leaf shall be green; and shall not be careful in the year of drought, neither shall cease from yielding fruit.
17:9 The heart is deceitful above all things, and desperately wicked: who can know it?
17:10 I the LORD search the heart, I try the reins, even to give every man according to his ways, and according to the fruit of his doings.
Paul