Persistent Spell( Forgotten Realms Campaign Setting, p. 37)
You make one of your spells last all day.
Extend Spell (PH) ,
A persistent spell has a duration of 24 hours. The persistent spell must have a personal range or a fixed range,(for example, comprehend languages or detect magic). Spells of instantaneous duration, spells with a range of touch, and spells whose effects are discharged cannot be affected by this feat. You need not concentrate on spells such as detect magic and detect thoughts to be aware of the mere presence or absence of the thing detected, but you must still concentrate to gain additional information as normal. Concentration on such a spell is a standard action that does not provoke an attack of opportunity. A persistent spell uses up a spell slot four levels higher than the spell's actual level.