Tradition
St. Ambrose
Letters
Book 63 › Section 99
99. Reward is not obtained by ease or by sleep. The sleeper does no work, ease brings no profit, but rather loss. Esau by taking his ease lost the blessing of the first-born, for he preferred to have food given to him rather than to seek it. Industrious Jacob found favour with each parent.
Source: Letters (New Advent)