Ecclesiastes 3:11 – 13
New American Standard Bible (NASB)
God Set Eternity in the Heart of Man
11 He has made everything appropriate in its time. He has also set eternity in their heart, yet so that man will not find out the work which God has done from the beginning even to the end.
12 I know that there is nothing better for them than to rejoice and to do good in one’s lifetime; 13 moreover, that every man who eats and drinks sees good in all his labor — it is the gift of God.
From BibleGateway.com: http://www.biblegateway.com/passage/?search=Ecclesiastes 3:11-13&version=NASB