One day, he was walking on the road and saw a certain man that was planting a carob tree. He said to him, 'How many years until this [tree] will be laden [with fruit]?' He said to him, 'Until seventy years.' He said to him, 'Is it obvious to you that you will live [another] seventy years?' He said to him, 'That man found the world with carob trees. In the same way as my fathers planted for me, I will also plant for my children.'