We have previously explained that for a woman to put her picture on Facebook pages or chat rooms or other websites is haraam for a number of reasons, which we have explained in fatwa no. 165186
If we add to that the fact that the woman is not properly covered, and is showing her hair or neck, or other charms, this is something that makes the sin worse and makes the prohibition more emphatic.
What appears to be the case is that “liking” what is published on a person’s social media page is a kind of approval of publishing these pictures, and at the very least the one who put up the picture will understand it as such, especially if the one who adds the like is a knowledgeable or religiously committed person, or one who appears outwardly to be righteous and committed.
The Prophet (blessings and peace of Allah be upon him) said: “Whoever among you sees an evil action, then let him change it with his hand [by taking action]; if he cannot, then with his tongue [by speaking out]; and if he cannot, then with his heart – and that is the weakest of faith.”
Abu Dawood narrated in his Sunan (4345) from al-‘Urs ibn ‘Ameerah al-Kindi that the Prophet (blessings and peace of Allah be upon him) said: “If sin is committed on earth, the one who sees it and hates it – or denounces it – is like one who was absent from it, and the one who is absent from it but approves of it is like one who sees it.”
Classed as hasan by al-Albaani in Saheeh al-Jaami‘, no. 689; it was also narrated in a mursal report.
Ibn Rajab al-Hanbali said: The one who witnesses a sin and hates it in his heart is like the one who did not see it, if he is unable to denounce it or change it verbally or by taking action. The one who is not present when it happens but approves of it is like the one who saw it and was able to denounce it or change it but did not do so. That is because approval of sins is one of the most abhorrent of forbidden matters, by which one fails to denounce the sin in one’s heart, which is obligatory for every Muslim and this is not waived for anybody under any circumstances whatsoever.
End quote from Jaami‘ al-‘Uloom wa’l-Hukam (2/245)
If a person adds a “like” for any of these pictures or the like, what expression of objection has he made towards the evil action that has been committed?
And Allah knows best.