佛說處處經 1.12

1.12

「佛不飛行，有四因緣：一者、勸弟子欲令精進；二者、欲令弟子聽經；三者、報宿命恩；四者、現相，是故不飛行。

"That the Buddha does not fly through the air is due to four nidānas: first, he encourages the disciples, wishing to make them vigorous; second, he wishes to cause the disciples to listen to the sūtras; third, he repays debts of gratitude from past lives; fourth, he displays marks; therefore he does not fly through the air.