John Gill Commentary Psalms 86:7

"In the day of my trouble I will call upon thee; For thou wilt answer me." — Psalms 86:7 (ASV)

In the day of my trouble I will call upon you
David had his troubles, both inward and outward, before and after he came to the throne, in private and public life; and every good man has his troubles; and there are some particular times or days of trouble; which trouble arises from different causes; sometimes from themselves, their corruptions, the weakness of their grace, and the poor performance of their duties; sometimes from others; from the persecutions of the men of the world; from the wicked lives of profane sinners, and especially professors of religion, and from the spread of false doctrine; sometimes from Satan and his temptations; and sometimes from the more immediate hand of God in afflictions, and from the hidings of his face.

These troubles do not last always; they are but for a day, for a particular time; and such a season is a fit one for prayer, and the Lord invites and encourages his people to call upon him in prayer when this is the case, (Psalms 50:15) . Christ had his times of trouble, in which he called upon his divine Father, (John 11:33John 11:41) (12:27)

for you will answer me ;
which the idols of the Gentiles could not do; Baal could not answer his priests, (1 Kings 18:26) , this the psalmist concluded, both from the promise of God, (Psalms 50:15) , and from his frequent experience, (Psalms 138:3) , a very encouraging reason or argument this to call on the Lord: Christ was always heard and answered, (John 11:41John 11:42) .