Fiqh-us-Sunnah Volume 2, Supererogatory Prayer, Fiqh 2.043.

The majority of the scholars lay down the same conditions and prerequisites for the prostration of recital as they do for the salah, with respect to purity, facing the qiblah, and covering the ‘aurah. Ash-Shaukani says: “There is no hadith concerning prostrations of recital which proves that to prostrate one must be in a state of purity [free from major or minor defilements]. The people who were with him [the Prophet] prostrated with him and he did not order any of them to perform ablution, and it is hard to believe that they all were in a state of purity. Furthermore, the polytheists prostrated with him and they are impure, and their ablution would not be acceptable. Al-Bukhari relates from Ibn ‘Umar that he would prostrate even when not free of minor impurities. Ibn Abi Shaibah recorded the same from him. As for the report from al-Baihaqi, (with a chain that Ibn Hajar calls sahih), which says: ‘A man is not to prostrate unless he is in a state of purity.’ These reports can be reconciliated by Ibn Hajar’s statement that this (either) refers to a major defilement or when an option is available, whereas in the first case it depends on (presence of defilement and) the need to wash. Similarly, there is no hadith which states that the clothes or place need to be pure. Concerning covering the ‘aurah and facing the qiblah if possible, there is no disagreement.

Ibn Hajar said in Fath al-Bari: “No one agrees with Ibn ‘Umar that one may make the sajdah without being clean of minor impurities, save ashSha’biy. Ibn Abi Shaibah related it from him with a sahih chain. He also recorded from Abu ‘Abdurrahman as-Salmi that he would recite an ‘ayyah of sajdah and then he would prostrate without ablution or facing the qiblah and while walking and just motioning only. Some among the Prophet’s household agree with Ibn ‘Umar.