Who we choose as our friends/companions is a serious decision that is not to be taken lightly. We should want friends who are on the same path as us and want the same things out of life that we do. Our ultimate goal is to do things fisibilillah(for the sake of Allah). It is our responsibly to make sure that we are careful with who we take as our close friends.
Most importantly we should make sure that our friends/companions are other Muslimahs. You want a friend who encourages the good(halal/permissible) and discourages the bad(haraam/forbidden). Another Muslimah will remind you when it's time to offer salah, encourage proper hijab, help you in constantly remembering Allah(swt). When we are around other Muslimahs we consistently dhikr(remember) Allah(swt). For example how we greet each other, when we sneeze, yawn, begin to do something. etc. These are just a few of the many benefits of having other Muslimahs as our close friends.
You may have been reading this and thinking to yourself "All my friends are Muslimahs so I don't have anything to worry about". In a perfect world this would be true but we also have to make sure that our fellow Muslimahs are on the same page with us as well. In a friendship you want someone who will pull you up not push down. A friend will encourage you to go to Islamic classes on the weekend instead of letting your time waste away on the dunya(worldly matters). A friend will help you find a husband the halal way, not encourage you to date/have a boyfriend. A friend will not talk about her friends(backbiting), she will remind you that when you backbite another it's like eating the flesh of your sister. The point is they will be a good influence on you and help you lead a successful life in this world that will insha' Allah lead to a successful life in the akhira.
Below is proof(daleel) from Quran and Hadith on the importance of being careful who we choose as our companions.
And the believers, men and women, are protecting friends of one another, they enjoin the right and forbid the wrong (9:71)
Allah the Exalted says in the Quran: "And (remember) the Day when the wrong-doer will bite his hands and say: Woe to me! Would that I had taken a path with the Messenger. Woe to me! If only I had not taken so- and- so as a friend! He has led me astray from this Reminder (the Quran) after it had come to me." [25:27-29].
The Prophet(saw) said: "Man is influenced by the faith of his friends. Therefore, be careful of whom you associate with." - Abu Dawood & Tirmidhi
In another Hadith, Prophet(saw) said: "The example of a good companion and a bad companion is like that of the seller of musk, and the one who blows the blacksmith's bellows (respectively). So as for the seller of musk then either he will grant you some, or you buy some from him, or at least you enjoy a pleasant smell from him. As for the one who blows the blacksmith's bellows then either he will burn your clothes or you will get an offensive smell from him." - Bukhari & Muslim
The Prophet(saw) said: "Help your brother whether he is a wrong-doer or is wronged". A man enquired: 'O Messenger of Allah (saw) , I may help him when he is wronged, but how can I help him when he is a wrong-doer? ' The Prophet (saw) said ' You can prevent him from wrong-doing. That will be your help to him" - Bukhari & Muslim
May Allah(swt) bless us all with companions who help us stay on the siratul mustaqeem(the straight path) - ameen
Anything we have said right is from Allah(swt) anything we have said wrong is from us.
Love for the sake of Allah
Nadira & Najwa