Mahâ-Parinibbâna-Suttanta: The Book of the Great Decease

'Not even that, O Lord!' 'You see then, Sâriputta, that you know not the hearts of the Arahat Buddhas of the past and of the future. Why therefore are your words so grand and bold? Why do you burst forth into such a song of ecstasy?' 17. 'O Lord! I have not the knowledge of the hearts of the Arahat Buddhas that have been, and are to come, and now are. I only know the lineage p. 14 of the faith. just, Lord, as a king might have a border city, strong in its foundations, strong in its ramparts and toranas, and with one gate alone; and the king might have a watchman there, clever, expert, and wise, to stop all strangers and admit only friends. And he, on going over the approaches all round the city, might not so observe all the joints and crevices in the ramparts of that city as to know where even a cat could get out. That might well be. Yet all living things of larger size that entered or left the city, would have to do so by that gate. Thus only is it, Lord, that I know the lineage of the faith. I know that the Arahat Buddhas of the past, putting away all lust, ill-will, sloth, pride, and doubt; knowing all those mental faults which make men weak; training their minds in the four kinds of mental activity; thoroughly exercising themselves in the sevenfold higher wisdom, received the full fruition of Enlightenment. And I know that the Arahat Buddhas of the times to come will [do the same]. And I know that the Blessed One, the Arahat Buddha of to-day, has [done so] now[1].'