暮鼓晨鐘

暮 evening, sunset
鼓 drum
晨 morning, dawn
鐘 bell

According to the Digital Dictionary of Buddhism, this is a Chinese idiom “describing a strict daily routine. It derives from the playing of bells and drums within a Chinese Buddhist monastery to mark the services throughout the day and the articulations of the monastic routine.” The Dictionary cites Charles Jones as the source for this.
http://www.buddhism-dict.net/cgi-bin/xpr-ddb.pl?66.xml+id(%27b66ae-9f13-6668-9418%27)

The website yellowbridge.com (“the premier guide to Chinese language and culture for English speakers”) gives the meaing as: “lit. evening drum, morning bell (idiom); fig. Buddhist monastic practice; the passage of time in a disciplined existence”
https://www.yellowbridge.com/chinese/dictionary.php?word=暮鼓晨鐘&cache=49707

The same definition can be found at purpleculture.com, chinesepod.com, ninchinese.com, etc:
https://www.purpleculture.net/dictionary-details/?word=暮鼓晨鐘
https://www.chinesepod.com/dictionary/暮鼓晨鐘
https://app.ninchanese.com/word/traditional/178923/暮鼓晨鐘