Majmu' al-Fatawa - Ibn Taimiya - (21/463)

He answered:

Praise be to Allah. He may not delay the prayer until its prescribed time has ended. If he can perform the ritual bath with cold or hot water, he must do so and pray within the prescribed time. Otherwise, he must perform dry ablution, for dry ablution out of fear of the cold is permissible by agreement of the imams. If he prays after performing dry ablution, he need not repeat the prayer. However, once he is able to perform the ritual bath, he must do so. Allah knows best.

He was asked:

A woman suffers from an eye condition and is burdened by excess body fat. She is unable to use the bathhouse because of her condition, and her husband will not let her purify herself, yet she wishes to pray. May she wash the healthy parts of her body and perform dry ablution for her head?

He answered:

Yes. If she cannot perform the ritual bath with either cold or hot water, she must pray within the prescribed time after performing dry ablution, according to the vast majority of scholars. However, the position of al-Shāfiʿī and Ahmad is that she must wash whatever she can and perform dry ablution for the remainder. The position of Abū Hanīfa and Mālik is that if she washes the greater part of her body, she need not perform dry ablution; but if she can wash only the smaller part, she should perform dry ablution and is not required to wash.

فَأَجَابَ: الْحَمْدُ لِلَّهِ لَا يَجُوزُ لَهُ تَأْخِيرُ الصَّلَاةِ حَتَّى يَخْرُجَ الْوَقْتُ بَلْ عَلَيْهِ إنْ قَدَرَ عَلَى الِاغْتِسَالِ بِمَاءِ بَارِدٍ أَوْ حَارٍّ أَنْ يَغْتَسِلَ وَيُصَلِّيَ فِي الْوَقْتِ وَإِلَّا تَيَمَّمَ: فَإِنَّ التَّيَمُّمَ لِخَشْيَةِ الْبَرْدِ جَائِزٌ بِاتِّفَاقِ الْأَئِمَّةِ وَإِذَا صَلَّى بِالتَّيَمُّمِ فَلَا إعَادَةَ عَلَيْهِ لَكِنْ إذَا تَمَكَّنَ مِنْ الِاغْتِسَالِ اغْتَسَلَ وَاَللَّهُ أَعْلَمُ. وَسُئِلَ: عَنْ امْرَأَةٍ بِهَا مَرَضٌ فِي عَيْنَيْهَا وَثِقَلٌ فِي جِسْمِهَا مِنْ الشَّحْمِ وَلَيْسَ لَهَا قُدْرَةٌ عَلَى الْحَمَّامِ؛ لِأَجْلِ الضَّرُورَةِ وَزَوْجُهَا لَمْ يَدَعْهَا تَطَّهَّرُ وَهِيَ تَطْلُبُ الصَّلَاةَ فَهَلْ يَجُوزُ لَهَا أَنْ تَغْسِلَ جِسْمَهَا الصَّحِيحَ؟ وَتَتَيَمَّمُ عَنْ رَأْسِهَا؟ . فَأَجَابَ: نَعَمْ، إذَا لَمْ تَقْدِرْ عَلَى الِاغْتِسَالِ فِي الْمَاءِ الْبَارِدِ وَلَا الْحَارِّ فَعَلَيْهَا أَنْ تُصَلِّيَ فِي الْوَقْتِ بِالتَّيَمُّمِ عِنْدَ جَمَاهِيرِ الْعُلَمَاءِ لَكِنَّ مَذْهَبَ الشَّافِعِيِّ وَأَحْمَد أَنَّهَا تَغْسِلُ مَا يُمْكِنُ وَتَتَيَمَّمُ لِلْبَاقِي. وَمَذْهَبُ أَبِي حَنِيفَةَ وَمَالِكٍ إنْ غَسَلَتْ الْأَكْثَرَ لَمْ تَتَيَمَّمْ وَإِنْ لَمْ يُمْكِنْ إلَّا غَسْلُ الْأَقَلِّ تَيَمَّمَتْ وَلَا غُسْلَ عَلَيْهَا.