四分律行事鈔資持記 2.1172

2.1172

五中。流汗有同鹹水，故亦須受。注中，上句決上臂汗，下句例成額汗。

In the fifth: flowing sweat is identical to salty water, so it must also be received. In the note, the upper sentence decides on sweat from the upper arm; the lower sentence by analogy establishes sweat from the forehead.