Istikharah

Sayyiduna Sa'd bin Abi Waqqas (may Allah be pleased with him) narrates that the Prophet (peace and blessings be upon him) said: "Part of the good fortune of the son of Adam is that he seeks guidance (istikharah) from Allah Almighty."
Ahmad, Abu Ya'la and al-Bazzar recorded it, except that he recorded these words: "Part of a man's good fortune is that he seeks guidance (istikharah) from his Lord and is content with what his Lord has decreed; and part of a man's misfortune is that he abandons istikharah and is displeased after the decree (of destiny)." The chain of this narration contains a narrator, Muhammad bin Abi Humayd. Ibn Adi says: Judging by the narrations he has transmitted, his weakness is evident, and his hadith is muqarib (passable); yet despite his weakness his hadith is to be written down. Ahmad, al-Bukhari (may Allah have mercy on him) and a group declared this man da'if (weak).

Sayyiduna Anas bin Malik (may Allah be pleased with him) narrates that the Prophet (peace and blessings be upon him) said: "Whoever seeks guidance (istikharah) is not disgraced, whoever seeks counsel does not come to regret, and whoever is moderate does not become poor."
Al-Tabarani recorded it in al-Mu'jam al-Saghir and al-Mu'jam al-Awsat.

Sayyiduna Abu Ayyub al-Ansari (may Allah be pleased with him) narrates that the Prophet (peace and blessings be upon him) said: "Keep the marriage proposal concealed. Then perform ablution and do it well, then pray as much as Allah Almighty has written for you, then praise your Lord and glorify Him, then say: 'O Allah! Indeed You have power and I have no power; You know and I do not know; and You are the Knower of the unseen. If You know that such-and-such a woman (here the man should name her) will be better for me in my world and my Hereafter, then decree her for me' (the narrator is in doubt; perhaps the words are:) 'ordain her for me.'"
Al-Tabarani recorded it in this form in al-Mu'jam al-Kabir, and all of its narrators are thiqat (trustworthy).

Sayyiduna Abu Ayyub al-Ansari (may Allah be pleased with him), who was a Companion of the Prophet (peace and blessings be upon him), narrates that the Prophet (peace and blessings be upon him) said to him: "Keep the marriage proposal concealed. Then perform ablution and do it well, then pray as much as Allah Almighty has written for you, then praise your Lord and glorify Him, and then recite: 'O Allah! Indeed You have power and I have no power; You know and I do not know; and You are the Knower of the unseen. If You know that such-and-such a woman (here the man should name her) will be better for me in my religion, my world and my Hereafter, then decree that she be mine' (the narrator is in doubt; perhaps the words are:) 'ordain her for me.'"
Ahmad recorded it; Ahmad also recorded it as "mawquf" (a Companion's own statement), as you see. Its chain contains a narrator, Ibn Lahi'ah, and he has been criticised. He also mentioned another chain for it whose narrators are thiqat (trustworthy), but he did not quote its wording; rather he said: A narration with this meaning has been reported.

Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) reports about the Prophet (peace and blessings be upon him): Whenever the Prophet (peace and blessings be upon him) intended to do something and sought guidance (istikharah) about it, he would recite: "O Allah! I seek Your guidance by Your knowledge, I seek ability through Your power, and I ask You of Your bounty. Indeed You have power and I have no power, You know and I do not know, and You are the Knower of the unseen. O Allah! If this matter is better for me in my religion, better for me in my livelihood, and better for me in that through which I seek good, then ordain well-being for me, make it easy for me, and then bless me in it. And if something other than this is better for me, then ordain for me what is good, wherever it may be." He (peace and blessings be upon him) would recite this and then make his decision.
Al-Tabarani recorded it in all three books, except that in al-Mu'jam al-Saghir he recorded these words: "Ordain good for me wherever it may be, turn evil away from me wherever it may be, and make me content with Your decree." The chain in al-Mu'jam al-Kabir contains a narrator, Salih bin Musa al-Talhi, and he is da'if (weak); the chain in al-Mu'jam al-Awsat and al-Mu'jam al-Saghir contains a narrator who has been declared da'if (weak) in hadith.

It is reported from Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) in al-Mu'jam al-Kabir, concerning the Prophet (peace and blessings be upon him), that when the Prophet (peace and blessings be upon him) was about to do something and wished to seek guidance (istikharah) about it, he would say; after this the narrator mentioned the hadith as before, except that he recorded these words: "Ordain well-being for me and make it easy for me."
Al-Bazzar recorded it with various chains, and in it he recorded these additional words: "I ask You of Your bounty and Your mercy, for both of them are in Your hand; no one besides You owns them." He also recorded these words: "Make it agreeable for me and make it easy." Two of its routes are reported with hasan (good) chains.

Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) narrates: The Prophet (peace and blessings be upon him), teaching us the istikharah, said: "O Allah! I seek Your guidance by Your knowledge, I seek ability (i.e. strength) from You by Your power, and I ask You of Your bounty. Indeed You have power and I have no power, You know and I do not know, and You are the Knower of the unseen. If this matter, such-and-such (here the man should name the matter), is better for me in my religion and my livelihood, better for me in the outcome of the matter, and better for me in all my affairs, then ordain it for me and bless me in it. And if something else is better for me, then ordain good for me wherever it may be, and make me content with it."
Al-Tabarani recorded it in al-Mu'jam al-Awsat. Its chain contains a narrator whose biography I have not found anyone giving.

Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) and Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) narrate: The Prophet (peace and blessings be upon him) used to teach us the istikharah just as he taught us a surah of the Qur'an. (The words of the istikharah are:) "O Allah! I seek Your guidance by Your knowledge and I seek ability through Your power. Indeed You have power and I have no power, You know and I do not know, and You are the Knower of the unseen. O Allah! Whatever decree You have passed upon me, make its outcome good for me."
Al-Tabarani recorded it in al-Mu'jam al-Kabir. Its chain contains a narrator, Abdullah bin Hani' bin Abi Ablah; Ibn Hibban mentioned him in the book "al-Thiqat", and he is muttaham (accused).

Sayyiduna Abu Sa'id al-Khudri (may Allah be pleased with him) narrates: I heard the Prophet (peace and blessings be upon him) say: "When one of you intends to do something, he should recite: 'O Allah! I seek Your guidance through Your knowledge, I ask You for Your power, and I ask You of Your bounty. Indeed You have power and I have no power, You know and I do not know, and You are the Knower of the unseen. O Allah! If this matter (here the man should mention the matter he intends to do) is better for me with regard to my religion, my livelihood and my Hereafter, then well and good; otherwise turn it away from me and turn me away from it, and then ordain good for me wherever it may be. Nothing can happen except with the help of Allah Almighty.'"
Abu Ya'la recorded it, and its narrators have been declared trustworthy. Al-Tabarani recorded a similar narration in al-Mu'jam al-Awsat.