Ruling on wearing a string around the neck, for men
Question

I see many young men, even my friends, wearing strings around their necks, to which is usually attached pictures of the martyrs, or slogans about Palestine or al-Aqsa… What is the ruling on wearing such things, for men, with or without images or pictures?
Praise be to Allah.These strings that are worn around the neck are either one of two things:
1. Either they have images of living beings, so it is not permissible to wear them, either for men or for women. Please see the answer to question no. 7222 for more information on the ruling on images.
2. Or they are free of images. If they are only worn by women, and there is nothing in then that is contrary to Islamic rulings, then there is nothing wrong with them.
But if they are for men, as the questioner mentioned, then it is not permissible for them to wear it, because wearing necklaces is something that is only for women, so wearing them is imitating women, and hardly anyone wears them in the manner in which women usually wear them except effeminate men (al-mukhannathun) – we seek refuge with Allah.
It is proven in the hadith of Ibn ‘Abbas (may Allah be pleased with him) that the Messenger of Allah (blessings and peace of Allah be upon him) cursed men who imitate women and women who imitate men. Narrated by al-Bukhari (5885).
Shaykh Muhammad ibn Salih al-‘Uthaymin (may Allah have mercy on him) was asked about the ruling on men wearing chains, and he replied:
Wearing chains as adornment is haram [for men], because that is something that is only for women, and he is imitating women. The Messenger of Allah (blessings and peace of Allah be upon him) cursed men who imitate women, and the prohibition and sin is exacerbated if it is made of gold, in which case it becomes haram for men on two counts, because it is gold and because it is imitating women. It becomes even more abhorrent if it contains an image of an animal or an angel, and even worse and more abhorrent than that is if it contains a cross. This is haram even for a woman, if she wears jewellery in which there is an image, whether it is an image of a human or an animal, a bird or not a bird, or if it contains the image of a cross. This – I mean wearing anything in which there is an image – is haram for both men and women, so it is not permissible for either of them to wear anything that contains the image of an animate being or the image of a cross. And Allah knows best."(Majmu‘ Fatawa Ibn ‘Uthaymin  11/97).
With regard to these pendants, even if we assume that the men do not intend to adorn themselves with them, it is still not free from imitating women in wearing necklaces, and resembling immoral and effeminate men in their actions and adornment. So it is more appropriate to tell men not to wear them at all, and instead of that they can wear these slogans without putting them on necklaces.
And Allah knows best.