「」。
"Trust me," he said.
Literal
"Trust-do [request-て]" [quotative-と] he [topic-は] said.
A minimal dialogue-attribution example. 信用して is the te-form of 信用する used as a soft imperative/request ('trust me'). The quotative と links the quote to 言った ('said'). Note the te-form request is direct but not rude — common in close relationships or at moments of emotional appeal.