Feet to Feet in Salah - Shaykh Hamza Yusuf

Ibn Hajar Al Asqalani (rah) stated: "The purpose of the Hadith of Nauman bin Bashir (ra) is to enforce strongly the straightening of rows and closing the gaps, it is not to encourage the joining of the feet and ankles." (Fathul Bari Shara Bukhari, vol 2, p 247/ Irshadul Sari Shara Bukhari, vol 2, p 368/ Umdadul Qari Shara Bukhari vol 5 p 295).

Feet to Feet, Toe to Toe by Shaykh Abdurrahman ibn Yusuf Mangera (For the full discussion read Fiqh al Imam: Key proofs in Hanafi Fiqh, page 45-52.
http://qa.sunnipath.com/issue_view.asp?HD=1&ID=997&CATE=4