Book of Jubilees 28:22
Then Jacob went in to Leah. She became pregnant and gave birth to a son for Jacob. He named him Issachar on the fourth (day) of the fifth month during the fourth year of the fourth week [2132]. She gave him to a nurse.
Then Jacob went in to Leah. She became pregnant and gave birth to a son for Jacob. He named him Issachar on the fourth (day) of the fifth month during the fourth year of the fourth week [2132]. She gave him to a nurse.