Spell
Spell
Use Scrolls, Wands, And Other Devices With Spell Completion Or Spell Trigger Activation As A Wizard Of One-Half Your Cleric Level (at Least 1st Level). For The Purpose Of Using A Scroll Or Other Magic Device, If You Are Also A Wizard, Actual Wizard Levels And These Effective Wizard Levels Stack.
WotC 3.5e
3.5e/PHB - Player's Handbook
Refs: 3.5e/PHB