คิดเล็กคิดน้อย
kít-lék-kít-náawy

คิด kít "to think"
เล็ก lék "small (in size)"
น้อย náawy "small (in number)/few"

the phrase altogether literally means "to think about small things and think about few things"

but properly translated means "to be petty, to split hairs, to sweat the small stuff," etc.