Rashi
Jewish
1040–1105
“the...villagers who do not dwell in walled cities, [celebrate] on the fourteenth, and those who dwell in walled cities [celebrate] on the fifteenth, like Shushan, and [these cities] must be surrounded [by walls] since the days of Joshua the son of Nun. So did our Sages expound and learn. and...sending Heb. וּמִשְּׁלֹחַ. This is a noun, like מִשְּׁמָר, watch, מִשְּׁמָע hearing. Therefore, the “shin” is vowelized soft (without a “dagesh”).”