A conversation between Sáriputta, Anuruddha and Moggallána in the Ketakivana in Sáketa, regarding the meaning of the word "sekha." A sekha is one who has only partially cultivated the four satipatthánas. S.v.174f.
Whoever cultivates psychic power, partially, can only do so by cultivating and developing the four bases of psychic power (iddhi-pádá). S.v.255.