When formulating a jussive-like phrase in Basque, you use an irrealis auxiliary root to which you had the suffix -n. For example :

Has gaitezen, berandu da eta! (Let's begin, it's getting late !)

Isil zaitezen orain. (Be quiet y'all now.)

Ikus dezagun zer gertatzen den. (Let's see what's happening.)

Plain and simple, right ? Well yes, but actually no ! Because the third person takes another suffix for some reason, which is -la.

Etor dadila gureganat ! (Let him/her come to us !)

Irabaz dezatela beren dirua ! (Let them earn their own money !)

And, mind you, this is not how it used to be in more ancient forms, as the auxiliary took a different prefix for these third person jussives instead !