First of all, just because there are foreign characters on the leather of the sofa doesn’t mean that it necessarily comes from a foreign and non-Muslim country and you shouldn’t be very doubtful in this regard.
Waswasah is in reality a mental illness that one must strive to keep away from.
In any case, the fiqhi ruling on your inquiry is as follows:
Leather products, such as the leather used on sofas, in bags, shoes, belts and anything else, and in general, any other animal parts that are used, such as bones, intestines, etc., if they come from an animal that is najis al-ayn (i.e., the animal itself is a najis substance, namely dogs and pigs), they will be najis for sure. Also, if the leather is produced by a non-Muslim country, even if from animals that aren't najis al-ayn and have halal meat, such as cows and sheep, they will still be najis because they haven't been slaughtered Islamically.
However, if the leather is produced in a Muslim country and doesn’t come from a najis al-ayn animal (dogs and pigs) and is exported to other countries and is used for other products, in this case, the leather will be considered pak (not najis) and using it will not bring about any complications, even if foreign characters have been printed on it or the sofa or whatever the product the leather has been used in, has been assembled or made in a non-Muslim country.
In the case of the sofa being made in a non-Muslim country, and we aren't sure whether the leather is the product of a Muslim or non-Muslim country, it cannot be considered pak. But if the sofa was made in a Muslim country and we do not know in what country (Muslim or non-Muslim) the leather was produced, then it is considered pak.
In any case, even if it turns out that the leather is indeed najis, it is still permissible to use it and there is nothing wrong with that.
It is with three conditions that you will become najis from the leather of the sofa:
1- You are sure that the leather of the sofa is najis (which we covered how to ascertain above).
2- The najis leather comes in contact with you.
3- Both you and the leather, or one of you is wet or damp to an extent that upon contact, the wetness of one transfers to the other. So if the dampness is so little that no transfer takes place, the pak object doesn't become najis.
In the case of you having doubt in any of these conditions, you won't become najis. In other words, until all three conditions are met, you won't become najis by the leather.
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