GUIContent.image

Description

The icon image contained.

    var icon : Texture;

    function OnGUI () {
        if(!icon) {
            Debug.LogError("Add a texture on the inspector first");
            return;
        }
        GUI.Button (Rect (0, 0, 100, 20), GUIContent (icon));
    }

using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour {
    public Texture icon;
    void OnGUI() {
        if (!icon) {
            Debug.LogError("Add a texture on the inspector first");
            return;
        }
        GUI.Button(new Rect(0, 0, 100, 20), new GUIContent(icon));
    }
}