question #2 Sahih Muslim 835d, Book 6, Hadith 365 : How did the Prophet Muhammad (peace be upon him) incorporate voluntary prayers into his daily routine?

We bear testimony to the fact that ‘A’isha said: Never was there a day that he (the Holy Prophet) was with me and he did not observe two rak’ahs of prayer in my house, i. e. two rak’ahs after the Asr.