Qamar dar Aqrab means Moon in Scorpio as an astrological event which occurs every month and is considered inauspicious for certain activities in our lives.
عِدَّةٌ مِنْ أَصْحَابِنَا عَنْ أَحْمَدَ بْنِ مُحَمَّدِ بْنِ خَالِدٍ عَنْ عَلِيِّ بْنِ أَسْبَاطٍ عَنْ إِبْرَاهِيمَ بْنِ مُحَمَّدِ بْنِ حُمْرَانَ عَنْ أَبِيهِ عَنْ أَبِي عَبْدِ اللَّهِ (عليه السلام) قَالَ مَنْ سَافَرَ أَوْ تَزَوَّجَ وَ الْقَمَرُ فِي الْعَقْرَبِ لَمْ يَرَ الْحُسْنَى.
A number of our companions, from Ahmad Bin Muhammad Bin Khalid, from Ali Bin Asbaat, from Ibrahim Bin Muhammad Bin Humraan, from his father, who has narrated the following:
Abu Abdullah-asws has said: ‘The one who travels or gets married whilst the moon is in the Scorpio (Qamar dar Aqrab) will never see the goodness’.[1]
[1] Al-Kafi, Vol. 8, H. 14864