Abandoning the Better (Tark al-Awla)
Abandoning the better or tark al-awlā (Arabic: تَرْک الأوْلی) is to do something good and abandon what is better to do. Shiite scholars do not take "abandoning the better" as a sin, and thus, they hold that prophets and Imams (a) might sometimes abandon the better. They maintain that in cases in which prophets and Imams (a) practiced istighfar (asking God for forgiveness), they did so because they had abandoned the better. In some verses of the Qur'an, some mistakes are attributed to some prophets. Exegetes of the Qur'an hold that since prophets are infallible; such mistakes are not sins from the standpoint of jurisprudence, rather they are "abandoning the better" (tark al-awla), that is, they just abandoned what the better action to do is.
"Abandoning the better" (tark al-awla) takes place when one has two options; one is good, and the other is better, but they do what is good and abandon what is better. The term was not used in the Qur'an and hadiths; rather, it was used by Muslim scholars. 
Difference with Sins
According to Tafsir-i nimuna, a sin is an action that counts as wrong for everyone, but "abandoning the better" is not wrong and is even favourable. Still, it is not good for some people to do because of their positions. For example, if a worker donates one day of his or her salary to construct a hospital, he has done a good thing. Still, if a wealthy person donates the same amount of money for constructing a hospital, he will be berated because he is expected to pay more, even though he has done something good in itself. Such an action is called "abandoning the better".
Abandoning the Better by Prophets and Imams (a)
The Shiites believe that prophets and Imams (a) are infallible, so they never commit major or minor sins; but they might sometimes abandon the better. The evidence for this is that the Qur'an refers to mistakes or slippages by prophets or their istighfar (asking God for forgiveness). For instance, according to Quran 2, the Satan misguided the prophet Adam (a) and then Adam practiced istighfar. Moreover, the Prophet Muhammad (s) and the Imams (a) have asked God for forgiveness in supplications transmitted from them. For example, there is a hadith according to which the Prophet (s) practiced istighfar one hundred times during a day and a night.
According to Shiite scholars, since there are rational arguments for the infallibility of prophets and the Imams (a), we cannot impute sins to them. Thus, the above cases should be construed as abandoning the better. They explain istighfars by prophets and the Imams (a) in terms of different categories and degrees of sins. For example, one category of sins is the judicial sin which is referred to in fiqh as forbidden. Another category is a failure to continuously think of God, which is not a judicial sin. Prophets and the Imams (a) never committed judicial sins because of their infallibility. Still, they could fail to continuously think of God because of their relationships with other people and the demands of their daily lives, and this led them to practice istighfar.
Examples in the Qur'an
The Qur'an has attributed actions to prophets (a) in terms such as "'usyan" (disobedience) and "zulm" (injustice or oppression) and their requests for God's forgiveness. Exegetes of the Qur'an have interpreted these cases as abandoning the better. Below are some Quranic verses in this regard, plus the interpretations of Quranic exegetes about them:
- Killing the Egyptian man by Moses (a): "He said, 'My Lord! I have wronged myself. Forgive me!' So He forgave him. Indeed, He is the All-forgiving, the All-merciful".
In this verse, the prophet Moses (a) asks for God's forgiveness because of killing a person, and according to the Qur'an, God forgives him. It is mentioned in Shia exegeses that the person who was killed by Moses (a) was a cruel companion of the Pharaoh, and so Moses (a) rightly killed him. According to this book, the man was bullying an Israelite person, and Moses (a) punched him once to defend the oppressed person, without the intention of killing. Thus, what he did was not a sin, but he had abandoned the better (tark al-awla) because it was careless in those circumstances and led him into unnecessary troubles.
- Abandoning his People by Yunus (a): "And [remember] the Man of the Fish (i.e. Yunus), when he left in a rage, thinking that We would not put him to hardship. Then he cried out in the darkness, 'There is no god except You! You are immaculate! I have indeed been among the wrongdoers!'"
This verse refers to the story of the prophet Yunus (a) (Jonah). He abandoned his people because of their disobedience and then regretted what he had done. He took his act to be an oppression of the people and then repented to God. According to 'Allama Tabataba'i, Yunus's (a) action was not oppression or a sin, indeed, and God punished him only to teach him not to do things that are slightly similar to oppression and sins. Yunus's (a) action was an instance of "abandoning the better".
- Eating from the forbidden tree by Adam (a): "Adam disobeyed his Lord, and went amiss".
According to Majma' al-bayan in its exegesis of this verse, "'usyan" literally means any disobedience of God. Thus, it includes not only the abandoning of one's obligations, but also the abandoning of recommended actions. Thus, Adam's (a) disobedience does not mean that he sinned. According to Tafsir-i nimuna, commands and prohibitions are sometimes "irshadi" or instructive; one case in point is when a physician tells a patient to take some medicine. In such a case, if the patient does not obey the physician's command, they only harm themselves. God's prohibition of eating the forbidden tree does not mean that its eating was a sin because God had not regulated obligations yet. Instead, it meant that eating the fruit would lead to Adam's (a) exit from the heaven to the Earth where he would suffer pains.
- Iḥtishāmīnīyā & Khushraftār, "Imām Riḍā wa tark-i awlā-yi anbīyāʾ", p. 26.
- Makārim Shīrāzī, Tafsīr-i nimūna, vol. 13, p. 324.
- Sayyid Murtaḍā, Tanzīh al-anbīyāʾ, p. 34.
- Then Satan caused them (Adam and Eve) to stumble from it (paradise), and he dislodged them from what they were in. We said, ‘Get down, being enemies of one another! On the earth shall be your abode and sustenance for a time.’ (Quran, 2:36)
- Ṣadūq, Maʿānī l-akhbār, p. 383-384.
- Subḥānī, Manshūr-i jāwīd, vol. 7, p. 288-289.
- Sharīfī & Yūsufīyān, Pajhūhishī dar ʿiṣmat-i ma'ṣūmān, p. 184-187, 330
- Qur'an, 28:16.
- Makārim Shīrāzī, Tafsīr-i nimūna, vol. 16, p. 42-43
- Qur'an, 21:87.
- Ṭabāṭabāyī, al-Mīzān, vol. 14, p. 314-315.
- Ṭabāṭabāyī, al-Mīzān, vol. 14, p. 315.
- Makārim Shīrāzī, Tafsīr-i nimūna, vol. 13, p. 485.
- Qur'an, 20:121.
- Ṭabrisī, Majmaʿ al-bayān, vol. 7, p. 56.
- Makārim Shīrāzī, Tafsīr-i nimūna, vol. 13, p. 323.
- Iḥtishāmīnīyā, Muḥsin & Khushraftār, Amīn. 1392 Sh. "Imām Riḍā wa tark-i awlā-yi anbīyāʾ dar Qurʾān". Majala-yi Safīna 41:25-49.
- Makārim Shīrāzī, Nāṣir. Tafsīr-i nimūna. Tehran: Dār al-Kutub al-Islāmīyya, 1374 Sh.
- Ṣadūq, Muḥammad b. ʿAlī al-. Maʿānī l-akhbār. Edited by ʿAlī Akbar al-Ghaffārī. Qom: Daftar-i Nashr-i Islāmī, 1403 AH.
- Sayyid Murtaḍā ʿAlam al-Hudā. Tanzīh al-anbīyāʾ wa l-aʾimma. Edited by Fāris Ḥasūn Karīm. Qom: Būstān-i Kitāb, 1380 Sh.
- Sharīfī, Aḥmad Ḥusayn & Ḥasan Yūsufīyān. Pajhūhishī dar ʿiṣmat-i ma'ṣūmān. Qom, Pajūhishgāh-i Farhang wa Andīsha-yi Islamī, 1377Sh.
- Subḥānī, Jaʿfar. Manshūr-i jāwīd. Qom: Muʾassisat Imām al-Ṣādiq, 1383 Sh.
- Ṭabāṭabāyī, Sayyid Muḥammad Ḥusayn al-. Al-Mīzān fī tafsīr al-Qurʾān. Qom: Daftar-i Nashr-i Islāmī, 1417 AH.
- Ṭabrisī, Faḍl b. al-Ḥasan al-. Majmaʿ al-bayān fī tafsīr al-Qurʾān. Tehran: Nāṣir Khusrū, 1372 Sh.