USE OF HANDS BY OFFENSIVE PLAYER
Article 2 An offensive player cannot
obstruct or impede an opponent by grasping him with his hands or
encircling any part of a defender’s body with his arms, except in the following situations:
(a) If he is a runner. A runner may ward off opponents with his hands and arms. He also may lay his hand
on a teammate or push him into an opponent, but he may not grasp or hold on to a teammate; or
(b) During a loose ball that has touched the ground. An offensive player may use his hands/arms legally
to block or otherwise push or pull an opponent out of the way in a personal attempt to recover the ball.
See specific fumble, pass, or kick rules and especially 6-2-1; or
(c) During a kick. A kicking team player may use his hands/arms to ward off or to push or pull a receiver
who is legally or illegally attempting to obstruct his attempt to proceed; or
(d) During a legal block.
Penalty: For illegal use of hands, arms, or body by the offense: Loss of 10 yards.
http://www.nfl.com/static/content/publi ... onduct.pdf