首楞嚴義疏注經 10.371

10.371

顯弘經時少也。一念，心之邊際也。夫弘經者時必長久，豈有一念而宣說者？今顯弘經力大，故舉至少以顯殊勝。

This reveals how brief the time of propagating the sūtra may be. A single thought-moment is the outermost margin of the mind. Now, propagating a sūtra normally requires a long time; how could one proclaim it in a single thought-moment? Here, to reveal that the power of propagating the sūtra is immense, the text cites the very least [duration] to display its extraordinary excellence.