A person is upon the way of his friend

1 - Allah Said:

{"Ah! Woe to me! If only I had never taken so-and-so as a friend! He indeed led me astray from the Reminder after it had come to me!"}[al-Furqan; 28-29]

2 - The Messenger of Allah said:

"A person is upon the way of his friend. So, let one of you look to whom he keeps as a friend." ['Sahih al-Jami'' (3545) and 'as-Silsilah as-Sahihah' (927)]

3 - 'Abdullah bin Ahmad bin Hambal said:

"My father went out to Tarsus on foot, and he perfored two or three Hajjs on foot, and he was the most patient of people upon being alone." ['Tarjamat al-Imam Ahmad'; p. 18]

4 - Ibn al-Qayyim said:

"Know that the greatest of losses is for you to be preoccupied with one who will bring you nothing but a loss in your time with Allah - the Mighty and Majestic - and being cut off from Him, a wasting your time with the person, a weakening of your energy, and the dispersing of your resolve. So, if you are tested with this - and you must be tested with this - deal with him according to how Allah would wish, and be patient with him as much as possible. Get closer to Allah and His Pleasure by way of this person, and make your getting together with him something to benefit from, not something to incur a loss from. Be with him as if you are a man who is on a road who was stopped by another man, who then asks you to take him on your journey. Make sure that you are the one who gives him a ride, and that he is not the one giving you the ride. If he refuses, and there is nothing to gain from travelling with him, do not stop for him, bid him farewell, and do not even turn back to look at him, as he is a highway robber, regardless of who he really is.

So, save your heart, be wary of how you spend your days and nights, and do not let the Sun set before you arrive at your destination." ['al-Wabil as-Sayyib'; p. 45]

5 - Ibn Jama'ah said:

"So, it is upon the student of knowledge to abandon socialization, as abandoning it is from the most important things that the student of knowledge must do - let alone with members of the opposite gender - especially with those who spend most of their time in play, and spend little of their time in thought, as the nature of individuals can rob you.

The harms of socialization include the passing of life without any benefit, as well as the decline of wealth and religious practice, if this socialization were to occur with the wrong people.

The student of knowledge should not mix except with either those who he can benefit, or can benefit from. And if he is offered the friendship of one who will waste his time with him, will not benefit him, will not benefit from him, and will not assist him in reaching his objective, he should politely end the relationship from the start before it progresses to something deeper, as when something becomes established, it becomes more difficult to change it. There is a phrase that is constantly on the tongues of the Fuqaha': 'Repelling something is easier than removing it.'

So, if he requires someone to befriend, let that person be righteous, religious, pious, wary, intelligent, full of benefit, having little evil, good at complying, rarely conflicting, reminding him if he forgets, cooperating with him when he is reminded, helpful if he is in need, and comforting if he is in distress."

['Tadhkirat as-Sami' wal-Mutakallim'; p. 83]

6 - Ibn Qudamah al-Maqdisi said:

"Know that not everyone is suitable to be your friend. You must verify that this potential friend has the neccessary characteristics that make friendship with him something to be desired. The one you seek to befriend must have five characteristics:

He must be intelligent, as there is no good in befriending an idiot, as he will only harm you when he wants to benefit you. By intelligent, we mean one who understands things as they are, either on his own, or if they are explained to him;

He must have good manners, and this is a must. One who is simply intelligent might be overcome by anger or desire, and obey his desire. Thus, there would be no benefit in befriending him;

He must not be a fasiq, as such a person would not fear Allah, and whoever does not fear Allah cannot be trusted;He must not be an innovator, as his abundance of innovation is feared from befriending him;He should not be eager for the dunya.

"['Mukhtasar Minhaj al-Qasidin'; p. 126-132]