أَخْبَرَنَا إِسْمَاعِيلُ بْنُ مَسْعُودٍ، قَالَ حَدَّثَنَا خَالِدٌ، عَنْ شُعْبَةَ، قَالَ أَخْبَرَنِي مَيْسَرَةُ بْنُ حَبِيبٍ، قَالَ سَمِعْتُ الْمِنْهَالَ بْنَ عَمْرٍو، يُحَدِّثُ عَنْ أَبِي عُبَيْدَةَ، عَنْ عَبْدِ اللَّهِ، أَنَّهُ رَأَى رَجُلاً يُصَلِّي قَدْ صَفَّ بَيْنَ قَدَمَيْهِ فَقَالَ أَخْطَأَ السُّنَّةَ وَلَوْ رَاوَحَ بَيْنَهُمَا كَانَ أَعْجَبَ إِلَىَّ ‏.‏

It was narrated from Abdullah that: He saw a man praying with his feet together. He said: "He is not following the Sunnah. If he were to shift his weight from one to the other I would like that better." Translation Not Available

Book Ref: Sunan An Nisai Book 11 Hadith 893
Web Ref:  Sunan An Nisai Vol 2 Book 11 Hadith 894