According to Hindu mythology, it is considered inauspicious to tie a rakhi during Bhadra Kaal, a particular time period. It is believed that tying a rakhi during this time can anger Shani and bring bad luck to the brother. However, there are conflicting opinions on this matter. Some sources suggest that sisters can tie rakhis during a short period when Bhadra Kaal is weak. The best time to tie a rakhi on Raksha Bandhan is during Aparahna, which is late afternoon according to the Hindu calendar. It is important to note that the bond of love and trust formed by tying a rakhi to a brother is the most beautiful aspect of this festival and cannot be expressed in words.