It was narrated from Abu Sa'eed Ar-Ru'aini that 'Abdullah bin Malik told him, that :
'Uqbah bin 'Amir told him, that his sister vowed to walk, barefoot and bareheaded, and he mentioned that to the Messenger of Allah ﷺ He said: "Order her to ride and to cover her head, and to fast for three days."

حَدَّثَنَا عَلِيُّ بْنُ مُحَمَّدٍ، حَدَّثَنَا عَبْدُ اللَّهِ بْنُ نُمَيْرٍ، عَنْ يَحْيَى بْنِ سَعِيدٍ، عَنْ عُبَيْدِ اللَّهِ بْنِ زَحْرٍ، عَنْ أَبِي سَعِيدٍ الرُّعَيْنِيِّ، أَنَّ عَبْدَ اللَّهِ بْنَ مَالِكٍ، أَخْبَرَهُ أَنَّ عُقْبَةَ بْنَ عَامِرٍ أَخْبَرَهُ أَنَّ أُخْتَهُ نَذَرَتْ أَنْ تَمْشِيَ حَافِيَةً غَيْرَ مُخْتَمِرَةٍ وَأَنَّهُ ذَكَرَ ذَلِكَ لِرَسُولِ اللَّهِ ﷺ فَقَالَ " مُرْهَا فَلْتَرْكَبْ وَلْتَخْتَمِرْ وَلْتَصُمْ ثَلاَثَةَ أَيَّامٍ " .