He should not meddle with things he doesn't understand.
meddle into
Frequency:
60
%
It's not wise to meddle into affairs that don't concern you.
meddle around
Frequency:
40
%
Stop meddling around and focus on your own work.
Idiomatic Expressions for meddle
Phrase: meddle with
Meaning: to interfere or tamper with something
Usage: Please don't meddle with the computer settings if you don't know what you're doing.