Bending the toes
    in sujood and sitting between the two sujood
Question

                My Mu-Alleem told our class that when you
      sujood, your toes should be bended and you are not allowed to put your feet on top of the
      other when you come to the sitting position Any-one leading the salaah and does not do the
      above, he's not aloowed to lead a salaah and we should not follow him in the salaah
Praise be to Allah.What your muallim (teacher) has told you, that in sujood the toes
    should be bent and should touch the ground, is correct. It is a proven part of the sunnah
    of the Prophet 
 (peace and blessings of Allaah be upon him). Al-Bukhaari (may Allaah
    have mercy on him) reported in his Saheeh from Abu Humayd al-Saaidi that the Prophet
    
 (peace and blessings of Allaah be upon him) when he prostrated the tips
    of his toes would be facing the qiblah (Fath, no. 828).
    Abu Dawood reported from Abu Humayd al-Saaidi:
     he would bend his toes when he prostrated. (Reported by Abu
    Dawood, no. 716, Bab fi iftitaah al-salaah). The author of Awn
    al-Mabood Sharh Sunan Abi Dawood said: He would bend (yaftukh)
    his toes  the meaning of fatkh is to bend or flex, so he would bend his
    toes and point them towards the qiblah. (Awn al-Mabood,
    2/419). The hadeeth was reported by al-Albaani in Sifat al-Salaah p.
    142, 1411 AH edition [This book is also available in English under the title The
    Prophets Prayer Described  Translator].
    Pointing the toes towards the qiblah is sunnah and is encouraged, but
    if a person does not do it, his prayer or leadership of the prayer is still valid,
    especially as many people do not have the ability to flex their toes in the manner
    described. But everyone should put their toes on the ground when prostrating, because they
    are counted among the seven parts of the body on which we are commanded to prostrate. If a
    person lifts his feet off the ground when prostrating, and does not place the tips of his
    toes on the ground, then his prayer or leadership of the prayer is not valid.
With regard to the way one should sit between sujoods, two ways of
    doing this have been narrated from the Prophet 
 (peace and blessings of Allaah be upon
    him).
Keeping the right foot upright and sitting on the left foot, as was
        described in the saheeh hadeeth which describes how he sat between two sujoods: He
        kept his right foot upright, and he pointed its toes towards the qiblah.
        This is the most well known way, and it is the way he sat most of the time.

Keeping both feet upright and sitting on the heels, as was described in
        the saheeh hadeeth which describes how he sat between two sujoods: Sometimes he
        would rest on both his heels and the balls on his feet. (See Sifat
        al-Salaah by al-Albaani, p. 152). This is not the way of sitting that
        is forbidden.
      
    
    If a person who is praying puts one foot on top of the other and sits
    on them, he is doing something other than the sunnah, but his prayer or leadership of the
    prayer is still valid. In all cases, we should guide people towards the sunnah and teach
    them about it, because this is an important matter  how could it be otherwise? The
    Prophet 
 (peace and blessings of Allaah be upon him) said: Pray as you have seen
    me praying. (Reported by al-Bukhaari, no. 631). And Allaah
    knows best.