Adding an image as the background of a shape

Question

I have this XML file with a background that has a gradient, round corners and a border:

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle" >

    <corners android:radius="14dp" />

    <gradient
        android:angle="45"
        android:centerColor="#7995A8"
        android:centerX="35%"
        android:endColor="#000000"
        android:startColor="#E8E8E8"
        android:type="linear" />

    <padding
        android:bottom="0dp"
        android:left="0dp"
        android:right="0dp"
        android:top="0dp" />

    <stroke
        android:width="3dp"
        android:color="#878787" />

</shape>

and it looks like this:

What I want to know is how can I make the background an image from my /drawable folder? Instead of the current gradient? I need to keep the border and the round corners. Thanks.