Wa `alaykum As-Salamu wa Rahmatullahi wa Barakatuh.
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
Dear brother in Islam, we would like to thank you for the great confidence you place in us. We implore Allah Almighty to help us serve His cause and render our work for His Sake.
First of all, it is to be stated that Allah has commanded us not to wear sewn clothes and not to cover our heads so that one shows utter humbleness and surrender to Allah. It has another great significance that it makes the person like a newborn wrapped in a piece of cloth. This, in fact, is a sign of being in dire need of Allah’s help and guidance in every matter.
Moreover, wearing these two pieces, a pilgrim remembers the state of people on the Day of Judgment when all people will stand naked and barefooted to be reckoned by Allah and either punished or rewarded.
Having understood some of the wisdom behind this, we should know that what is forbidden to wear during the state of ihram is not stitched materials in themselves but those garments that are made to fit the limbs and are usually worn by people in normal state, such as shirts, pants and T-shirts. Therefore, there is nothing wrong with wearing a stitched belt.
Explaining this, Dr. Yunus al-Astal, Professor of Fiqh at the Islamic University, Gaza, Palestine, states:
"It is permissible to wear a belt over the izar (waist wrapper) for the purpose of holding the izar or keeping money and other needs. There is nothing wrong with this even if it is stitched. This is because what is forbidden is stitched clothes that are habitually worn when one is not in the state of ihram."
The eminent Saudi scholar, Sheikh Ibn al-`Uthaymeen adds:
"There is nothing wrong with wearing a belt over the izar (waist wrapper). With regard to the questioner saying that it is stitched, this comment is based on a misunderstanding, because some of the common folk think that what is meant by it is anything that has stitches in it, but that is not correct. Rather what the scholars mean by wearing things that are stitched is that which is made to fit the limbs and is worn in the manner in which such garments are usually worn, such as shirts, pants and T-shirts, etc. The scholars did not mean that which has stitches in it. Hence, if a person were to enter ihram in a patched rida' (upper garment) and a patched izar, there would be nothing wrong with that, even though part of it is stitched to another part."
Excerpted, with slight modifications, from: www.islam-qa.com