16 Heb “while he allows himself to be found.” The Niphal form has a tolerative force here.
17 Heb “Let the wicked one abandon his way.” The singular is collective.
18 Heb “and the man of evil his thoughts.” The singular is collective.
19 Heb “let him return.” The singular is collective, meaning “let them.”
20 The imperfect with vav (ו) conjunctive after the jussive indicates purpose/result.
21 The appeal and promise of vv. 6–7 echoes the language of Deut 4:25–31; 30:1–10; and 1 Kgs 8:46–53, all of which anticipate the exile and speak of the prerequisites for restoration.

In other versions

“Seek the Lord while he may be found;

call upon him while he is near;

let the wicked forsake his way,

and the unrighteous man his thoughts;

let him return to the Lord, that he may have compassion on him,

and to our God, for he will abundantly pardon.

Seek the Lord while he may be found;

call on him while he is near.

Let the wicked forsake their ways

and the unrighteous their thoughts.

Let them turn to the Lord, and he will have mercy on them,

and to our God, for he will freely pardon.

Seek the Lord while he may be found;

call to him while he is near.

Let the wicked one abandon his way

and the sinful one his thoughts;

let him return to the Lord,

so he may have compassion on him,

and to our God, for he will freely forgive.

Seek the Lord while you can find him.

Call on him now while he is near.

Let the wicked change their ways

and banish the very thought of doing wrong.

Let them turn to the Lord that he may have mercy on them.

Yes, turn to our God, for he will forgive generously.

Seek Yahweh while he lets himself be found;

call him while he is near.

Let the wicked forsake his way,

and the man of sin his thoughts.

And let him return to Yahweh, that he may take pity on him,

and to our God, for he will forgive manifold.

Seek ye the Lord while he may be found,

Call ye upon him while he is near:

Let the wicked forsake his way,

And the unrighteous man his thoughts:

And let him return unto the Lord, and he will have mercy upon him;

And to our God, for he will abundantly pardon.

Public Domain