PATIENCE OR SABR IN ISLAM
Patience according to dictionary means the capacity to accept or tolerate delay, trouble, or suffering without getting angry or upset is called as patience. 
SABR is an Arabic word for Patience which comes from a root meaning to detain, refrain and stop. In the spiritual sense, patience means to stop ourselves from despairing and panicking, to stop our tongues from complaining, and to stop our hands from striking our faces and tearing our clothes at times of grief and stress. 
Patience is one of the best qualities a man can possess; if we take a close look at everything happening around us, we can surely conclude that patience is the solution for them all. Be it a severe downfall in business or certain unavoidable circumstances, we can handle them all with the divine tool of patience! It is said that patience is a virtue but in today’s time, patience has taken an altogether a different outlook, people mix patience with laziness. Being patient does not mean being lazy, but being calm in setting goals that would lead to success.
The Glorious Qur’an has given a lot of emphasis on patience and has given glad tidings to those who are patient. One who is patient earns Allah’s mercy, blessings and guidance. “Allah surely loves those who are the Sabireen (patient).” (Qur’an.Surah Aa’le Imran 3:146)
“And be patient, indeed Allah is with the patient ones.” (Qur’an.Surah Anfal 8:46)
“Nay, seek (Allah’s) help with patient perseverance and prayer: It is indeed hard, except to those who bring a lowly spirit, Who bear in mind the certainty that they are to meet their Lord, and that they are to return to Him. ” [Qur’an.Surah Baqarah 2:45-46] 
Prophet Muhammad (صلى الله عليه و سلم) is the best and ultimate human example of being patient. He personifies patience. Prophet Muhammad صلى الله عليه و سلم went to a city not far away from Makkah, known as Ta'if. He went there to preach Islam to the locals and approached the leaders of Ta'if and called them towards Islam. Not only did the leaders reject the call to Islam but they reacted in such a way that they set young children upon the Prophet Muhammad (May Allah honour Him and grant Him peace) to taunt him, stone him and chase him out of Ta'if. The Prophet Muhammad (May Allah honour Him and Grant Him peace) bled till his footwear was drenched in blood, Angel Jibreel (Peace be upon Him) came to the Prophet and said, “If you wish, then I will give the order for two angels to crush the residents of Ta'if between the two mountains in which it lies.” The Prophet replied in the negative and said, “I am hopeful that their descendants will accept Islam.” Allahu Akbar. This was the patience of our beloved Prophet Muhammad (May Allah honour Him and grant Him peace).Sahih Al Muslim 4425. 
Patience and Shakwah (complaint)
Shakwah (complaint) falls into two categories: The first type means to complain to Allah, and this does not contradict patience. It is demonstrated by several of the Prophets, for example, when Ya qub (alaihi wa sallam) said:
"I only complain of my distraction and anguish to Allah." (Yusuf 12:86).
Earlier, Ya'qub (alaihi wa sallam) had said "sabrun jamil" which means "patience is most fitting for me." The Qur'an also tells us about Ayyub:
"And (remember) Ayyub (Job), when he cried to his Lord, 'Truly distress has seized me. (al-Anbiya 21:83).
The epitome of patience, the Prophet (Sallallaahu alaihi wa Sallam), prayed to his Lord: " O Allah, I complain to You of my weakness and helplessness." Musa (alaihi wa sallam) prayed to Allah, saying: "O Allah, all praise is due to You, and complaint is made only to You, and You are the only One from Whom we seek help and in Whom we put our trust, and there is no power except by Your help." The second type of complaint involves complaining to people, either directly, through our words, or indirectly, through the way we look and behave. This is contradictory to patience.
Some scholars have defined patience as a good human characteristic or a positive psychological attitude, by virtue of which we refrain from doing that which is not good. Human beings cannot live a proper, healthy life without patience.
Abu 'Uthman said: "the one who has patience is the one who has trained himself to handle difficulties."
'Amr ibn 'Uthman al-Makki said: "Patience means to keep close to Allah and to accept calmly the trials He sends, without complaining or feeling sad."
Ibn al-Qayyim said: “The best life is attained by the blessed through patience, and they rise to the highest degrees through their gratitude.”
Another scholar said: "Patience means to refrain from complaining."  
Patience is of three types:
(i) Patience upon obedience –
To be patient when finding it hard obeying Allah’s commandments. Example: Allah wants us to wake up early for Fajr prayers and while establishing this as our daily routine we need to be extremely patient, we need not lose hope but we have to strive hard in following Allah’s command and being obedient to Him.
(ii) To be patient when a trouble befalls you. For example -
When we suffer acute losses in business, wealth or property, we have to be very patient and have trust in Him alone. Nothing happens without His will. This life is a test and Allah is with those who are patient.
(iii) To be patient when finding it hard to abstain from sins - For example:
When a person has fallen a trap to bad habit of watching movies, listening to music etc, and strives hard to refrain from it and urges himself to abandon the bad habit, Allah would Insha’Allah help him in practicing patience and he would be rewarded.