《太平广记·卷二百五十六·嘲诮四》
这匹白马如果是在雪天把它放出，你是别想找到的，如果是在月夜，也只能看到它的鞍子。
雪中放出空寻迹，月下牵来只见鞍。
If this white horse is released on a snowy day, you won't be able to find it; if it's on a moonlit night, you'll only be able to see its saddle.