Silence

From LSWiki

[Spell      :] Silence
[Level      :] Two
[Reversible :] Yes
[Sphere     :] Conjuring
[Components :] None
[Usage      :] cast silence [-]
[Effect     :] Upon casting silence the cleric conjures a
                mystickal force which prevents all speech in the
                area.  Beware though, many of your own spells
                require that you are able to speak in order to 
                cast them.  Casting the reverse of silence will
                banish an aura of silence if one is present in
                the area.