One Who Has Only an Impure Garment
One who has only an impure garment for his prayer: does he pray in it, or pray uncovered?
Hanafi
If a quarter of it or more is pure, he must pray in it and may not pray uncovered; if less than a quarter is pure, he may choose between praying in it and praying uncovered, though praying in it is better.
Reference: Al-Hidāyah — Radd al-Muḥtār — Tabyīn al-Ḥaqāʾiq
Maliki
He prays in it and does not repeat the prayer if the time is short; repeating it within the time is recommended if the time is ample.
Reference: Al-Mudawwanah — Al-Sharḥ al-Kabīr — Mawāhib al-Jalīl
Shāfiʿī
He does not pray in the impure garment; rather, he prays uncovered, performing all the pillars in full, and need not repeat the prayer.
Reference: Al-Umm — Minhāj al-Ṭālibīn — Al-Majmūʿ
Hanbali
He prays in it and does not pray uncovered, and he must repeat the prayer, because the purity of the garment is a condition he did not fulfil.
Reference: Al-Mughnī — Al-Kāfī — Kashshāf al-Qināʿ