Is it permissible to dedicate a thread in forums to pray for a sick member?

It is permissible to ask others to supplicate (make du'a) for you, but with the following considerations: that a person does not make it a habit, thus becoming lazy in supplicating for themselves; that one does not fear that the person asked might become conceited or self-admiring; and that the intention behind it is to benefit both oneself and the person asked, because the angels say "Amen" to his supplication when he supplicates for his brother in his absence. So, if a Muslim asks his brother for a supplication, his intention should be to benefit the person being asked by enabling him to perform a good deed through his supplication for his brothers. As for one who asks for supplication solely to benefit himself, his action is permissible but contrary to what is preferable. Ibn Taymiyyah clarified that whoever instructs another to supplicate with the intention of benefiting both the one instructed and the one instructing, then he is following the Prophet's example. However, if the intention is merely to seek a need without intending to benefit the other person and be kind to them, then this is among the less preferred forms of asking, and abandoning it is better.