大般涅槃經義記 1.137

1.137

上來自為，下明為他。「拯」猶濟也。因說廣濟，名拯無量苦惱眾生。

The above was for himself; below clarifies what is for others. 'Saving' (zheng) is like rescuing. Because the preaching saves widely, it is called saving immeasurable suffering beings.