وقف خدمت نمایند. I think this is the verb, It means they provide for people during their 4years of being in parliament.

Past: نمايندگان مجلس خود را در چهار سال نمايندگي وقف خدمت به مردم نمودند

Present: نمايندگان مجلس خود را در چهار سال نمايندگي وقف خدمت به مردم می نمايند

The second one is not used much.

You can say ''وقف خدمت به مردم بکنند'' but it s not formal that much and with نمایند it sounds more polite.

Verb conjugation

نمايند what does this verb mean?

نمايندگان مجلس خود را در چهار سال نمايندگي وقف خدمت به مردم نمايند

What would be its conjugation in present and past? I looked up this word on google and didn't get anything :/

نمایند is a formal verb and simply means do. 

but this verb conjugation mens: do your best for people.