Praise be to Allaah.
The answer to this question is to see what the Messenger of
Allah (blessings and peace of Allah be upon him) did when he sent out
daa‘iyahs to call people to Islam. He (blessings and peace of Allah be
upon him) sent the daa‘iyahs to call the people to Islam, and he taught
them to start first of all with Tawheed or the Oneness of Allah, then the
prayer, then zakaah, then fasting, then Hajj when the time for it came. He
sent Mu‘aadh to Yemen and told him to call them first of all to Tawheed,
belief in the Oneness of Allah. If they responded to that, then he was to
call them to pray. If they responded to that, then he was to call them to
give zakaah. He did not mention fasting and Hajj because when he sent
Mu‘aadh, it was not the time for these acts of worship, as he sent him in
Rabee‘ al-Awwal of 10 AH. There was still some time to go before Hajj, and
also fasting. The Prophet (blessings and peace of Allah be upon him) in
his wisdom did not want to spring all the rulings of Islam at once on
those who were being called to the faith. This is part of the wisdom
mentioned in the verse (interpretation of the meaning): “Invite
(mankind, O Muhammad صلىالله عليه وسلم)
to the way of your Lord (i.e. Islâm) with wisdom” [al-Nahl 16:125].
But should one start, straight after a person has entered
Islam, with rulings on minor issues such as the beard, isbaal (letting the
hem of one’s clothes come below the ankle) and so on?
This should be based on what is referred to above, that the
best of guidance is the guidance of Muhammad (blessings and peace of Allah
be upon him). So he should start first of all with the basics of Islam,
until Islam is settled in his heart and he is at ease in his new faith. At
that point we may teach him other matters, starting with the most important,
then the next most important and so on. This is the way of Allah with regard
to both shar‘i rulings and laws of nature. Look how the foetus begins to
grow bit by bit, and the four seasons change bit by bit, and the sun rises
and sets similarly. If we were to teach all the rulings and so on all at
once, it would take a long time and it may put him off the religion of
Islam. End quote.
Shaykh Ibn ‘Uthaymeen (may Allah have mercy on him)