Fiqh-us-Sunnah Volume 2, Supererogatory Prayer, Fiqh 2.092.
Section : Looking at something which distracts attention.
‘Aishah reports that the Messenger of Allah prayed in a cloak which had some designs on it. He said: “These designs have distracted me. Take [this cloak] to Abu Jahm [i.e., the person who gave it to the Prophet] and bring me a plain cloak.” This is related by al-Bukhari and Muslim.
Al-Bukhari records that Anas said: “‘Aishah had a curtain to cover [the doorway of] her house. The Prophet said to her: ‘Remove your curtain for its pictures always distract me during my prayers.'” This hadith proves that looking at some writing or design does not invalidate the salah.