Puberty by age

Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) said: On the day of Uhud, the Messenger of Allah (peace and blessings be upon him) looked me over for fighting when I was fourteen years old, and he (peace and blessings be upon him) did not permit me. Then when the time of Khandaq came, I was fifteen years old, and he (peace and blessings be upon him) permitted me. Later I came to Umar bin Abd al-Aziz (may Allah have mercy on him), who was the caliph in those days, and narrated this hadith to him. He said: This is the dividing line between the young and the grown-up. And he wrote to his governors: Make (the allotment) due to those who are fifteen, and attach those who are younger than that to their families as dependents.

Ubaydullah (may Allah have mercy on him) narrated the like of the aforementioned hadith, except that it has this addition: "And on the day of Khandaq he looked me over when I was fifteen years old, and he (peace and blessings be upon him) let me go." Nafi' (may Allah have mercy on him) said: I came to Umar bin Abd al-Aziz (may Allah have mercy on him), then he narrated the hadith, and he also said: "And whoever is younger than that, put him with his family as a dependent."

Ibn Jurayj narrated it from Ubaydullah bin Umar and added, at his words "he did not permit me": "and he did not consider me to have reached puberty." Otherwise it is like the aforementioned hadith, except that it does not have the words "dependents".
Ibn Sa'id said: In this hadith there is an unusual (gharib) wording, namely his saying: "and he did not consider me to have reached puberty."

Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) said: On the day of Uhud I was presented before the Messenger of Allah (peace and blessings be upon him), and at that time I was fourteen years old, and he (peace and blessings be upon him) considered me too young. Then the following year, at the time of Khandaq, I was presented, and at that time I was fifteen years old, and he (peace and blessings be upon him) let me go to fight. In a hadith of Sahih Muslim the words are: "He (peace and blessings be upon him) considered me too young and sent me back to the boys."

Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) said: The Messenger of Allah (peace and blessings be upon him) looked me over on the day of the Battle of Uhud, when I was fourteen years old. He (peace and blessings be upon him) considered me too young and sent me back among the boys. When the day of the Battle of Khandaq came, he (peace and blessings be upon him) looked me over, and by then I had become fifteen years old. He (peace and blessings be upon him) permitted me to take part in jihad. Ubaydullah said: And Umar bin Abd al-Aziz (may Allah have mercy on him) wrote that those of fifteen years should be included in the obligation (of jihad). Another hadith has these words: The Prophet (peace and blessings be upon him) accepted Sayyiduna Ibn Umar and Sayyiduna Rafi' bin Khadij (may Allah be pleased with them both) on the day of the Battle of Khandaq, and at that time they were fifteen years old.

Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) said: On the day of Badr I was presented before the Prophet (peace and blessings be upon him) when I was thirteen years old, and he (peace and blessings be upon him) did not include me among the fighters. Then I was presented on the day of Uhud, when I was fourteen years old, and he (peace and blessings be upon him) did not include me among the fighters. Then I was presented on the day of Khandaq, when I was fifteen years old, and he (peace and blessings be upon him) included me among the fighters.

Ibn Shihab (may Allah have mercy on him) said: These are the military expeditions (maghazi) of the Messenger of Allah (peace and blessings be upon him): the Battle of Badr took place in Ramadan, 2 AH. Then he (peace and blessings be upon him) fought the Battle of Uhud in Shawwal, 3 AH. In 4 AH he fought the Battle of Khandaq, which is also called al-Ahzab, and the Battle of Banu Qurayzah. Then in Sha'ban, 5 AH, he fought the Battles of Banu al-Mustaliq and Banu Lihyan; in 6 AH, the Battle of Khaybar. In Ramadan, 8 AH, the Conquest of Makkah, and in Shawwal, 8 AH, the Battle of Hunayn and the siege of the people of Ta'if. Then the narrator mentioned the rest of the hadith.

Urwah (may Allah have mercy on him) said: This is an account of the military expeditions of the Messenger of Allah (peace and blessings be upon him) in which he waged jihad. (Through another chain,) Ibn Shihab (may Allah have mercy on him) said: This is an account of the military expeditions of the Messenger of Allah (peace and blessings be upon him) in which he waged jihad.

Imam Malik bin Anas (may Allah have mercy on him) said: The Battle of Badr took place a year and a half after he (peace and blessings be upon him) came to Madinah upon emigrating, the Battle of Uhud a year after that, Khandaq four years after, Banu al-Mustaliq five years after, the Battle of Khaybar in the sixth year, Hudaybiyah in that same year, the Conquest of Makkah in the eighth year, and the Battle of Banu Qurayzah took place in the year of Khandaq.

Muhammad bin Ishaq said: The Battle of Uhud took place in Shawwal, 3 AH, and the Battle of Khandaq in Shawwal, 5 AH. The Shaykh said: Regarding the Battle of Khandaq, the view of Urwah, Ibn Shihab and Malik bin Anas is that it took place in 4 AH. This is better than the view of whoever says that the Battle of Khandaq took place in 5 AH, because their view agrees with the hadith of Sayyiduna Ibn Umar (may Allah be pleased with them both). However, the scholars have tried to reconcile the two views: the Battle of Uhud took place two and a half years after the Hijrah and Khandaq four and a half years after it; whoever said four years meant after completing four years and before the fifth year had ended; and the one who said five years. Sayyiduna Ibn Umar's (may Allah be pleased with them both) saying "I was 14 years old" meant that he had entered his fourteenth year, and his saying regarding the Battle of Khandaq "I was 15 years old" meant that he had completed 15; but he did not mention the excess, because they understood it from the context and understood fifteen years without the excess. And Allah knows best.
And this is more correct in my view, because it has been reported that there were two years between Uhud and Khandaq.

Sayyiduna Abu Hurayrah (may Allah be pleased with him) narrates in a marfu' form: "The pen has been lifted from three: from the boy until he has a wet dream; and if he does not have a wet dream, then until he becomes eighteen years old."
Sayyiduna Anas (may Allah be pleased with him) narrates in a marfu' form: "When a boy becomes fifteen years old, the prescribed punishments (hudud) will be established upon him."
Muhammad bin al-Qasim al-Taikani mentioned the first of these within a long fabricated (mawdu') hadith, and this Muhammad bin al-Qasim was known for fabricating hadith; we seek refuge with Allah from being forsaken. The chain of the Anas narration is weak; it is not sound.