The Messenger of Allah ﷺ forbade to make a vow. He said: It has not effect against fate, it is only from the miserly that it is means by which something is extracted. Musaddad said: The Messenger of Allah ﷺ said: A vow does not avert anything (i.e. has no effect against fate).  

أَخَذَ رَسُولُ اللَّهِ ﷺ يَنْهَى عَنِ النَّذْرِ ثُمَّ اتَّفَقَا وَيَقُولُ لاَ يَرُدُّ شَيْئًا وَإِنَّمَا يُسْتَخْرَجُ بِهِ مِنَ الْبَخِيلِ قَالَ مُسَدَّدٌ قَالَ رَسُولُ اللَّهِ ﷺ النَّذْرُ لاَ يَرُدُّ شَيْئًا  

The Messenger of Allah ﷺ as saying: A vow does not provide for the son of Adam anything which I did not decree for him, but a vow draws it. A Divine decree is one which I have destined, it is extracted from a miser. He is given what he was not given before.  

أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ لاَ يَأْتِي ابْنَ آدَمَ النَّذْرُ الْقَدَرَ بِشَىْءٍ لَمْ أَكُنْ قَدَّرْتُهُ لَهُ وَلَكِنْ يُلْقِيهِ النَّذْرُ الْقَدَرَ قَدَّرْتُهُ يُسْتَخْرَجُ مِنَ الْبَخِيلِ يُؤْتَى عَلَيْهِ مَا لَمْ يَكُنْ يُؤْتَى مِنْ قَبْلُ