KJV - The is nigh unto all them that call upon him, to all that call upon him in truth.
NLT - The is close to all who call on him,
Call Upon Him in Truth
Why would the psalmist repeat the phrase 'call upon Him' with an addition of 'in truth' ? I think it's to catch our attention, to give us pause to contemplate coming to Him in prayer. Instead of the formality of merely saying our prayers; we are to call upon Him with sincere hearts, humbling ourselves before Him as we worship our Creator, and realizing He is awaiting us to approach with our supplications.
From Reformation Bible Study:
While God is kind to all creation, the psalm goes on to specify those who love Him and turn to Him.
From Matthew Henry's commentary:
The proviso is very reasonable. He will hear and help us, (1.) If we fear him, if we worship and serve him with a holy awe of him; for otherwise how can we expect that he should accept us? (2.) If we call upon him in truth; for he desires truth in the inward part. We must be faithful to God, and sincere in our professions of dependence on him, and devotedness to him. In all devotions inward impressions must be answerable to the outward expressions, else they are not performed in truth.
What does this verse speak to you?