‘Venerable Nāgasena, that one quality of the Sal-tree which you say he ought to take, which is it?’

‘Just, O king, as the Sal-tree grows within the ground to the depth of a hundred cubits or more; just so, O king, should the strenuous Bhikshu, earnest in effort, perfect in solitude the four Fruits of Samanaship, the four Discriminations, the six forms of transcendental Insight, and all the qualities befitting a recluse. This, O king, is the one quality of the Sal-tree he ought to have. For it was said, O king, by Rāhula, the Elder:

“The tree that’s called the Sal-tree grows above the earth,
And shoots beneath, a hundred cubits deep.
As in the fullness of time, and at its highest growth
That tree shoots in one day a hundred cubits high,
Just so do I, O Buddha, like the Sal,
Increase, in solitude, in inward good.”’