The feat Cutpurse (Dragon Compendium Volume 1 95) has as its normal entry the following:
Using Sleight of Hand in melee provokes an attack of opportunity.
The feat Master Pickpocket (City of Stormreach 95) has as part of its benefit the following:
Your mastery of Sleight of Hand allows you to steal an object from an adjacent opponent in combat as a standard action without provoking attacks of opportunity.
However, the Player's Handbook, Dungeon Master's Guide,1 Monster Manual,2 and Rules Compendium don't mention explicitly that employing the skill Sleight of Hand provokes an attack of opportunity.
Although Use Skill is listed as usually provoking on Table 8–2: Actions in Combat (PH 141), the explanation says, "The individual skill descriptions in Chapter 4 tell you what sorts of actions are required to perform skills" (145), and in that chapter skill uses are said to provoke or not (e.g. feint (68), drawing a hidden weapon (82)).
The Rules Compendium on Actions in Combat under Use Skill has the note, "The skill’s description defines the action required and the effect. Disable Device, Heal, Open Lock, Search, and Use Rope provoke attacks of opportunity" (9), omitting the skill Sleight of Hand.
What is the source of the rule that says using the skill Sleight of Hand to steal an object provokes an attack of opportunity?
1 If you've Combat Reflexes, those pickpockets are dead (DMG 102).
2 A babau has the skill Sleight of Hand +11, an ethereal filcher +12, and a tiefling warrior +1. So watch your coin purse around demons and filchers, I guess?