《吕氏春秋·纪·季夏纪》
实行这些政令，这个月就会下及时雨，除去晦朔，三月中可以有两天降雨。
行之是令，是月甘雨三至，三旬二日。
If these policies are carried out, it will rain in due time this month, excluding the months’ beginning and end, there will be two rainfalls during the three months.