(Devarim 11:11) "But the land whither you are crossing to inherit it is a land of mountains and plains." Can it be that the verse speaks demeaningly of Eretz Yisrael in mentioning mountains? It is, therefore, written "and plains." Just as plains (are mentioned) for commendation, so, mountains. Furthermore, a reason is given for "mountains" as a reason is given for plains — the fruits of the mountain are quick (to grow) and those of the valley are fat.