Shaykh Al-Islam says, regarding the Allies of Allah:

"The allies of Allah do not have any special appearance with which they differ from other people. They have no special dress other than just being permissible dress, and are not distinguished by shaving of hair, or cutting it short, or braiding it, as long as it is within the permissible. Thus it has been said: "So many truthful believers in rough dress, and so many apostates in beautiful cloaks." Rather, the allies of Allah are to be found in all categories of the nation of Muhammad, except for the fact that they may not be found among the people of blatant innovations (bid'a) and moral corruption. They are found among people of the Qur'an, scholars, just as they are found among the fighters of jihad with weapons, and they are found among the businessmen, the manufacturers, and the farmers."

Taken From: The Criterion Between the Allies of the Merciful and the Allies of the Devil, pg. 37

Shaykh Al-Islam Ibn Taymiyyah, Rahimahullah, said:

"The religion that has been revealed is none other than the religion that Allaah, the Mighty and Magnificent, has legislated whereas the people of misguidance follow a religion that does not concord to the legislation that has been revealed and neither do they have knowledge of it. Indeed all they do is follow their vain desires and all they find that would satisfy their base desires."

From: Tawheed: A Great Principle

Shaykh al-Islam – may Allaah have mercy on him – said:

“If a man is following Abu Haneefah or Maalik or al-Shaafa’i or Ahmad, and he sees that the view of another madhhab concerning a given matter is stronger, and he follows that, then he has done well, and that does not detract from his religious commitment or good character. There is no scholarly dispute on this point. Rather this is more in accordance with the truth and is more beloved by Allaah and His Messenger.” 

Al-Fataawa, 22/247

Imam Ibn al-Qayyim al-Jawziyyah said:

"O you of little resolve, where do you stand upon this path? Adam found it difficult and Nuh lamented because of it, while Allaah’s Khaleel Ibraaheem was thrown into a pit of fire due to it. Isma’eel was laid upon his side ready to be sacrificed for its sake, and while upon it Yusuf was sold for a cheap price and then falsely cast into prison for many years. Zakariyah was sawed in half, and Yahya was slaughtered due to it. Ayyub suffered great distress, while Dawood cried copiously, and ‘Isaa cured the wretched poor of their diseases and walked with wild beasts due to it. And how many, how many forms of difficulty and hardship did the Messenger Muhammad (sallallaahu 'alayhi wa sallam) face while proceeding upon it – yet you live through amusements and distractions!"

[al-Fawaaid: Page 41]

Imam Ibnul Qayyim al-Jawziyyah (rahimahullah) said: 

“[Such a person] does not become disheartened by those who differ from and oppose him, as they are lesser in importance and significance, even if they might be greater in number, as some of the Salaf said: “Traverse the paths of the truth, and do not be discouraged by the small number of people who do the same.” Every time you feel disheartened by your being alone on this path, then look to those who came before you and strive to catch up with them, and turn away from everyone else, as they will not benefit you in the least with Allah. If you happen to see them somewhere along the path that you are upon, then do not turn to look at them, for if you do so, they will distract you and simply delay your progress.” 

['Madarij as-Salikin'; 1/21]

Ibn Hazm al-Andalusi (rahimahullah) wrote in Al-Akhlâq wa’l-Siyar (Morals and Behavior):

"When you give advice, do not give it only on condition that it will be taken. Do not intercede only on the condition that your intercession is accepted; do not make a gift only on the condition that you will be recompensed. Do it only in order to practice virtue, and to do what you should do when giving advice, interceding and being generous." 

Shaqiq bin Ibrahim said:

“While we were with Ibrahim bin Adham, a man passed by us and Ibrahim asked, ‘Is not that man so-and-so?’ and he was answered in the positive. Ibrahim said to a man in the gathering, ‘Catch up with him and tell him that Ibrahim asks, ‘Why did you not greet us with the Salam?’ That man said in reply, ‘By Allaah, my wife has just delivered a baby and I do not have anything, so I went out unaware of my surroundings.’ The man, returned to him and told what happened, and Ibrahim commented, ‘We all belong to Allaah! How is it that we were unaware about the condition of our friend until his condition deteriorated to this point?’

Ibrahim said to a man who was present, ‘Go to so-and-so and borrow two dinars from him, then go to the market and buy whatever is possible with a dinar and then give him. That man said, ‘I went to the market and bought whatever I could with one dinar and then went to the man’s house. I knocked the door and his wife asked, ‘Who is this?’ I said, ‘I need your husband.’ She said, ‘He is not here right now.’ I said, ‘Then open the door and go inside.’ She opened the door, and we took whatever we carried on the camel inside her house and gave her the second dinar. She asked, ‘Who sent all this?’ I said, ‘Your brother (in Islam) Ibrahim bin Adham.’ She said, ‘O Allaah! Do not forget what happened today from Ibrahim.’”

Transcribed from: Sifaatus-Safwah, vol. 4, p.155

Imam al-Hassan Al Basri said: 

 "We laugh and yet – who knows? – perhaps Allah has looked at some of our works and said: “I will not accept anything from you.” Woe to you, son of Adam! Can you fight Allah? Whoever disobeys Allah is fighting Him. By Allah! I have met seventy veterans of Badr. Most of their garments were wool. Had you seen them you would have said they are crazy, and had they seen the best among you they would have said: “Those people will have no part in the Hereafter.” Had they seen the worst among you they would have said: “Those people do not believe in the Day of Reckoning.” I have seen people for whom this world was cheaper than the dust under their feet. I have seen people the like of whom would come home at night, not finding more than his own portion of food, and yet say: “I shall not put all of this into my belly. I shall certainly give some away for Allah’s sake.” Then he would give away some of his food in charity, even if he were more in need of it than its recipient."

Narrated from `Alqama ibn Marthad by Abu Nu`aym in Hilya al-Awliya’ (1985 ed. 2:134).

Al-Haafidh Ibn Katheer said:

"Allaah subhanahuu, rejects those who refused Allaah's Shareeah; the laws that are good for the Muslims; the laws that forbid what is evil. Allaah rejects those who follow laws of personal desires and who adopt laws of Kufr such as the laws enforced by the Tartars who were under the control of Gengiz Khan, their king. These laws were a mixture of Judaism, Christianity and laws chosen by their king that suited his desires. Should we prefer these laws to the Sharee`ah of Allaah and His Prophet (sallallahu alaihi wa sallam)?

WHOEVER adopts laws other than Allaah's is a Kaafir and the Muslims must declare war on him until the laws of Allaah are adopted; the laws prescribed by Allaah and His Prophet (sallallahu alaihi wa sallam)"

Tafseer bn Katheer Vol.2/67