Rigidbody.sleepVelocity
var sleepVelocity: float;
float sleepVelocity;
sleepVelocity as float
Description

The linear velocity, below which objects start going to sleep. (Default 0.14) range { 0, infinity }.

See Rigidbody Sleeping for more information.
	rigidbody.sleepVelocity = 0.1;
using UnityEngine;
using System.Collections;

public class Example : MonoBehaviour {
    void Example() {
        rigidbody.sleepVelocity = 0.1F;
    }
}
import UnityEngine
import System.Collections

public class Example(MonoBehaviour):

	def Example() as void:
		rigidbody.sleepVelocity = 0.1F