Dear brother, I have a question regarding the authenticity of some narrations. These hadiths are the following:
1. The Messenger of Allah, sallallaahu ‘alayhi wa sallam, explained the Tafseer (explanation) of this verse to ‘Ali, may Allah be pleased with him, thus, "O ‘Ali, whatever calamity befalls you, illness, afflication, or any worldly calamity, it is the earning of your own hands."
2. Hasan, may Allah be pleased with him, reports that the Messenger of Allah, sallallaahu ‘alayhi wa sallam, said, "By the One in Whose Hand my life is, any scratch, twitching of veins, slipping of the foot, or a flying stone suddenly striking the body, all are due to the committing of sins."
3. Abu Musa, may Allah be pleased with him, reports that the Messenger of Allah, sallallaahu ‘alayhi wa sallam, said, "A wound or any slighter calamity is due to the commission of sins."
I want to know whether the above three hadiths are authentic? And what are their sources? May Allah bless you and reward you.

All perfect praise be to Allah, the Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.

The first hadeeth was cited by Imam Ahmad in his Musnad. It reads: 

"Marwaan ibn Muʻaawiyah Al-Fazaari narrated that Al-Azhar ibn Raashid Al-Kaahili narrated from Al-Khidhr ibn Al-Qawwaas, from Abu Sukhaylah, that ʻAli said, 'Shall I inform you of the best verse in the Quran which the Prophet, sallallaahu ‘alayhi wa sallam, told us about? It is the verse that reads (what means): {And whatever strikes you of disaster - it is for what your hands have earned; but He pardons much.} [Quran 42:30] The Prophet, sallallaahu ‘alayhi wa sallam, said, ‘I will interpret it for you, O ʻAli: it means that whatever strikes you of sickness, punishment or trial in this world, it is for what your hands have earned; and Allah is too generous to punish you again in the Hereafter. Whatever Allah pardons in this world, Allah is too forbearing to punish it after having pardoned you.’'" [Ahmad]

Shuʻayb Al-Arnaa’oot said, "Its chain of narration is weak. Al-Azhar ibn Raashid Al-Kaahili was declared a weak reporter by Ibn Maʻeen. Abu Haatim classified him as Majhool (one whose trustworthiness cannot be affirmed by Hadeeth scholars), and Al-Khidhr ibn Al-Qawwaas is also Majhool, and likewise is Abu Sukhaylah."

Ahmad Shaakir classified it as Hasan (good) in Al-Musnad as it was narrated through a different chain of narration cited by Al-Haakim on the authority of ʻAli. Al-Haakim classified it as authentic and meeting the conditions of Al-Bukhaari and Muslim. Ath-Thahabi agreed with Al-Haakim in classifying it as authentic.

The second hadeeth reads, "Any scratch, twitching of veins, slipping of the foot, or a flying stone suddenly striking the body, all are due to the committing of sins." It was cited by Al-Bayhaqi in his book Shuʻab Al-Imaan on the authority of Qataadah and Al-Hasan Al-Basri, as cited in Kanz Al-ʻUmmaal. It is a Mursal hadeeth (incompletely transmitted), which is a category of weak ahaadeeth. It was also cited by Ibn ʻAsaakir on the authority of Al-Baraa'. Al-Albaani classified it as Mawdhooʻ (fabricated) in his book Dhaʻeef Al-Jaamiʻ, no. 5209 and in As-Silsilah Adh-Dhaʻeefah, no. 1796. He commented on it, saying:

"It was cited by Ibn ʻAsaakir (8/182/1) on the authority of Muhammad ibn Al-Fadhl, from As-Salt ibn Bahraam, from Shaqeeq, from Al-Baraa's, as a Marfooʻ hadeeth (i.e. a hadeeth that is directly attributed to the Prophet, sallallaahu ‘alayhi wa sallam). I say: this chain of narration is very weak, given the presence of Muhammad ibn Al-Fadhl, known as Ibn ʻAtiyyah, who was known to be a liar ... A fellow scholar, may Allah reward him, guided me to another chain of narration in a recent publication, namely Az-Zuhd penned by Hannaad, who wrote (1/249/431), 'Muʻaawiyyah narrated on the authority of Ismaaʻeel ibn Muslim, from Al-Hasan, as a Marfooʻ hadeeth.' I say: Although it is a Mursal report narrated on the authority of Al-Hasan Al-Basri, the narrator from him is Ismaaʻeel ibn Muslim, the Makkan, who was known to be a weak reporter."

The third hadeeth was narrated on the authority of Abu Moosa, who related that the Prophet, sallallaahu ‘alayhi wa sallam, said, "Never does a disaster strike a servant (of Allah), whether it is grave or simple, except due to a sin; and Allah pardons much more." He, sallallaahu ‘alayhi wa sallam, then recited the verse: {And whatever strikes you of disaster - it is for what your hands have earned; but He pardons much.} [Quran 42:30]

At-Tirmithi cited this hadeeth and commented on it, saying, "This is a Ghareeb hadeeth (a hadeeth or version reported by one reliable or unreliable narrator which differs in context with another hadeeth or version reported by a group of reliable narrators) and we do not know it except through this chain of narration."

Al-Albaani classified it as having a weak chain of narration, then he classified it as Hasan in his book Saheeh Al-Jaamiʻ no. 7732 - 2843.

Allah knows best.