The Prophet (ﷺ) used to teach us the Istikhara for each and every matter as he used to teach us the Suras
from the Holy Quran. (He used to say), "If anyone of you intends to do something, he should offer a
two-rak`at prayer other than the obligatory prayer, and then say: 'Allahumma inni astakhiruka
bi'ilmika, wa astaqdiruka biqudratika, wa as'aluka min fadlika-l-'azim, fa innaka taqdiru wala aqdiru,
wa ta'lamu wala a'lamu, wa anta'allamu-l-ghuyub. Allahumma in kunta ta'lamu anna hadha-lamra
khairun li fi dini wa ma'ashi wa 'aqibati `Amri (or said, fi 'ajili `Amri wa ajilihi) fa-qdurhu li, Wa in
kunta ta'lamu anna ha-dha-l-amra sharrun li fi dini wa ma'ashi wa 'aqibati `Amri (or said, fi ajili `Amri
wa ajilihi) fasrifhu 'anni was-rifni 'anhu wa aqdur li alkhaira haithu kana, thumma Raddani bihi," Then
he should mention his matter (need).
Sahih al-Bukhari Book 80, Hadith 77
When the Hawazin delegation came to Allah's Messenger (ﷺ) after they had embraced Islam and requested
him to return their properties and war prisoners to them, Allah's Messenger (ﷺ) said, "To me the best talk is
the truest, so you may choose either of two things; the war prisoners or the wealth, for I have delayed
their distribution." Allah's Messenger (ﷺ) had waited for them for over ten days when he returned from Ta'if.
So, when those people came to know that Allah's Messenger (ﷺ) was not going to return to them except one
of the two things the said, "We choose our war Prisoners 'Allah's Messenger (ﷺ) stood up amongst the
Muslims, and after glorifying Allah as He deserved, he said, "Now then, these brothers of yours have
come to us with repentance, and I see it logical that I should return their captives to them, so whoever
of you likes to do that as a favor then he can do it, and whoever amongst you likes to stick to his
share, let him give up his prisoners and we will compensate him from the very first Fai' (i.e. war booty
received without fight) which Allah will give us." On that, all the people said. 'O Allah's Messenger (ﷺ)s We
have agreed willingly to do so (return the captives)" Then Allah's Messenger (ﷺ) said to them "I do not know
who amongst you has agreed to this and who has not. You should return and let your leaders inform
me of your agreement." The people returned and their leaders spoke to them, and then came to Allah's
Apostle and said, "All the people have agreed willingly to do so and have given the permission to
return the war prisoners (without Compensation)" (Az-Zuhri, the sub-narrator states) This is what has
been related to us about the captives of Hawazin.
Sahih al-Bukhari Book 57, Hadith 40
"The people asked 'Abdullah too many questions one day, and 'Abdullah said: 'There was a time when we did not pass so many judgments, but now that time is over. Now Allah, the Mighty and Sublime, has decreed that we reach a time when, as you see, (we are asked to pass many judgments). Whoever among you is asked to pass a judgment after this day, let him pass judgment according to what is in the Book of Allah. If he is faced with a matter that is not mentioned in the Book of Allah, let him pass judgment according to the way His Prophet passed judgment. If he is faced with a matter that is not mentioned in the Book of Allah and concerning which His Prophet did not pass judgment, then let him pass judgment according to the way the righteous passed judgment. If he is faced with a matter that is not mentioned in the Book of Allah, and concerning which His Prophet and the righteous did not pass judgment, then let him strive to work it out, and let him not say 'I am afraid, I am afraid.' For that which is lawful is clear and that which is unlawful is clear, and between them are matters which are not as clear. Leave that which makes you doubt for that which does not make you doubt.'"
Sunan an-Nasa'i Book 49, Hadith 19
that 'Umar bin Al-Khattab was asked about this Ayah: And when your Lord brought forth from the Children of Adam, from their loins, their seed and made them testify as to themselves: "Am I not your Lord?" They said: "Yes! We testify," lest you should say on the Day of Resurrection: 'Verily, we have been unaware of this (7:172).'" So 'Umar bin Al-Khattab said: "I heard the Messenger of Allah (ﷺ) being asked about it. So the Messenger of Allah (ﷺ) said: 'Indeed Allah created Adam, then He wiped his back with His Right Hand, and his offspring came out of him. So he said: "I created these for Paradise, and they will do the deeds of the people of Paradise." Then He wiped his back, and his offspring came out of him. So He said: "I created these for the Fire, and they will do the deeds of the people of the Fire." A man said: 'Then of what good is doing deeds O Messenger of Allah!' The Messenger of Allah (ﷺ) said: 'Verily, when Allah created a man for Paradise, He makes him perform the deeds of the people of Paradise, until he dies doing one of the deeds of the people of Paradise. So Allah will admit him into Paradise. And when He created a man for the Fire, He makes him perform the deeds of the people of the Fire until he dies doing the deeds of the people of the Fire. So Allah will enter him into the Fire.'"
Jami` at-Tirmidhi Book 47, Hadith 127
Who will kill Ka'b b. Ashraf? He has maligned Allah, the Exalted, and His Messenger. Muhammad b. Maslama said: Messenger of Allah, do you wish that I should kill him? He said: Yes. He said: Permit me to talk (to him in the way I deem fit). He said: Talk (as you like). So, Muhammad b. Maslama came to Ka'b and talked to him, referred to the old friendship between them and said: This man (i. e. the Holy Prophet) has made up his mind to collect charity (from us) and this has put us to a great hardship. When be heard this, Ka'b said: By God, you will be put to more trouble by him. Muhammad b. Maslama said: No doubt, now we have become his followers and we do not like to forsake him until we see what turn his affairs will take. I want that you should give me a loan. He said: What will you mortgage? He said: What do you want? He said: Pledge me your women. He said: You are the most handsome of the Arabs; should we pledge our women to you? He said: Pledge me your children. He said: The son of one of us may abuse us saying that he was pledged for two wasqs of dates, but we can pledge you (cur) weapons. He said: All right. Then Muhammad b. Maslama promised that he would come to him with Harith, Abu 'Abs b. Jabr and Abbad b. Bishr. So they came and called upon him at night. He came down to them. Sufyan says that all the narrators except 'Amr have stated that his wife said: I hear a voice which sounds like the voice of murder. He said: It is only Muhammad b. Maslama and his foster-brother, Abu Na'ila. When a gentleman is called at night even it to be pierced with a spear, he should respond to the call. Muhammad said to his companions: As he comes down, I will extend my hands towards his head and when I hold him fast, you should do your job. So when he came down and he was holding his cloak under his arm, they said to him: We sense from you a very fine smell. He said: Yes, I have with me a mistress who is the most scented of the women of Arabia. He said: Allow me to smell (the scent on your head). He said: Yes, you may smell. So he caught it and smelt. Then he said: Allow me to do so (once again). He then held his head fast and said to his companions: Do your job. And they killed him.
Sahih Muslim Book 32, Hadith 146