Invitatory

a.	1.	Using or containing invitations. The "Venite" [Psalm xcv.], which is also called the invitatory psalm. - Hook.
n.	1.	That which invites; specifically, the invitatory psalm, or a part of it used in worship.

Adj.

1.

invitatory - conveying an invitation; "a brief invitatory note"

inviting