Musar for Taanit 54:9
ריש לקיש אמר מפני נשמה יתירה דאמר ריש לקיש נשמה יתירה ניתנה בו באדם בע"ש במוצאי שבת נוטלין אותה ממנו שנאמר (שמות לא, יז) שבת וינפש כיון ששבת וי אבדה נפש:
prayed over the sacrifice of their brethren that it may be favourably accepted, whilst the men of the Ma'amad assembled in their synagogues and observed four fasts, on Monday, Tuesday, Wednesday and Thursday of that week. On Monday [they fasted] for those that go down to the sea; on Tuesday for those who travel in the deserts; on Wednesday that croup may not attack children; on Thursday for pregnant women and nursing mothers, that pregnant women should not suffer a miscarriage, and that nursing mothers may be able to nurse their infants; on Friday they did not fast out of respect for the Sabbath; and certainly not on the Sabbath.