Question: Is there any voluntary fast on black days 27th, 28th, and 29th every month of the lunar calendar?
Thank you for your question. I have not heard or read anything at all about fasting during the phases of the new moon. Please see this link about fasting during the white days:
And here is the du’a that is sunna to recite upon seeing the new moon:
However, if one wanted to fast on those days, without specifically ascribing it as a sunna of the Prophet, Allah bless him and grant him peace, one is free to do so.
I pray this helps.
Checked and Approved by Shaykh Faraz Rabbani
Ustadha Shazia Ahmad lived in Damascus, Syria for two years where she studied aqidah, fiqh, tajweed, tafseer, and Arabic. She then attended the University of Texas at Austin, where she completed her Masters in Arabic. Afterward, she moved to Amman, Jordan where she studied fiqh, Arabic, and other sciences. She recently moved back to Mississauga, Canada, where she lives with her family.