Aslam

Praise be to Allah.We would like to congratulate you and offer praise to Allaah for the

blessings He has bestowed upon you by guiding you to the Straight Path. We ask Him to help

us and you to be steadfast in adhering to this religion.

You do not have to use soap at all when doing wudoo. The word

wash which you have read in the books you refer to does not mean using soap or

any other kind of cleanser.

Shaykh Ibn Uthaymeen (may Allaah preserve him) said:

Washing the hands and face with soap when doing wudoo is not

prescribed in shareeah. On the contrary, it is a kind of obstinate and excessive

zeal. It was reported that the Prophet

(peace and blessings of Allaah be upon him) said:

Those who are obstinate and excessively zealous are doomed. He said it three

times.

If there is some kind of dirt on the hands that can only be removed by

using soap or some other cleanser, there is nothing wrong with using it in this case, but

under ordinary circumstances, using soap when doing wudoo is a kind of excessive

zeal and bidah (innovation), so it should not be used. (Fataawaa Islamiyyah,

1/223)

With regard to changing a babys diaper, if you mean the act of

changing itself, this does not affect the validity of one's wudoo.

If you mean that it involves touching something that is naajis (impure,

i.e. the babys urine and stools), this does not affect your wudoo either,

because there is no connection between touching something naajis and the validity of

ones wudoo. It has been reported that there is scholarly consensus on this

point, as stated in the book Al-Awsat by Ibn al-Mundhir (1/203). All one has to do

is wash one's hands to get rid of any naajis material.

If you mean that it involves touching the childs private parts,

whether the child is a boy or a girl, in the case of a child under the age of two years,

the rulings on awrah (that which is to be covered) do not apply, as the scholars

have stated, so if you touch them, this does not affect your wudoo. And Allaah knows

best.