1 Corinthians 14:13
Wherefore let him that speaketh in an [unknown] tongue pray that he may interpret.
Note 17 at 1Co 14:13: Given his statement in the previous verse, Paul was encouraging these believers to put ministry to the body ahead of personal ministry. "He that speaketh in an unknown tongue edifieth himself; but he that prophesieth [see note 12 at 1Co 14:5] edifieth the church" (1Co 14:4, brackets mine).
In context, Paul was speaking about interpreting a message in tongues in the church assembly. However, as discussed in note 5 at 1Co 14:2, we can also pray and receive interpretation of our tongues in our private prayer lives too.