A person should be extremely careful to avoid the prohibition of Shaatnez (mixed wool and linen), and he should check with “seven enquiries” which material was used for the sewing thread, for many tailors sew their clothes with linen thread, and this causes many sins. He should check in every way possible, until he is sure that there is no mixture of wool and linen. Chazal say that one who wears Shaatnez even for one small period of time, is punished that his prayers will not be listened to, G-d forbid. Every person must therefore be very careful with his clothes for the Honor of Hashem, his Creator.