I have heard that on one occasion the Blessed One was staying near Savatthi, in Jeta's Grove, Anathapindika's monastery. Now at that time Ven. Sariputta was sitting not far from the Blessed One, his legs crossed, his body held erect, having mindfulness established to the fore. The Blessed One saw Ven. Sariputta sitting not far away, his legs crossed, his body held erect, having mindfulness established to the fore.

Then, on realizing the significance of that, the Blessed One on that occasion exclaimed:

Just as a mountain of rock,
is unwavering, well-settled,
so the monk whose delusion is ended,
like a mountain, is undisturbed.