Allah azzawajal is Al-Hakeem (the perfectly wise). Owner of the infinite wisdom. we humans with our finite minds can only try to ponder and contemplate on the signs which He has shown us. Allah azzawajal says in the glorious quran ;
Verily, Allah is Ever All-Knowing, All-Wise. [76:30] (translated mohsin khan)
keeping this in mind i will try to clarify on this a little more, insha Allah.
TAFSIR OF THE VERSE
according to the following tafsir works, this verse(or part of it) was revealed regarding Abu-Bakr.
- Tanwîr al-Miqbas min Tafsir Ibn Abbas
- tafsir Al-Jalalayn
- Asbab Al-Nuzul by Al-Wahidi
i believe it is worthy to mention from Al-Wahidi as it provides us an understanding about the context we are discussing, the age factor, insha Allah.
(…till, when he attaineth full strength and reacheth forty years…) [46:15]. 'Ata' reported that Ibn 'Abbas said: “This verse was revealed about Abu Bakr al-Siddiq, may Allah be well pleased with him. He had travelled with the Messenger of Allah, Allah bless him and give him peace - when he was eighteen years old and the Messenger of Allah, Allah bless him and give him peace, was twenty - to Syria for trade. When they reached a place where there was a lotus tree, the Messenger of Allah, Allah bless him and give him peace, sat under the shade of this tree while Abu Bakr went to a monk nearby to ask him about religion. The monk then asked Abu Bakr: 'Who is that man under the shade of the lotus?' Abu Bakr said: 'He is Muhammad ibn 'Abd Allah ibn 'Abd al-Muttalib'. The monk said: 'By Allah, he is a Prophet. No one sat under the shade of this tree after Jesus, son of Mary, except Muhammad the Prophet of Allah'. At that moment, certainty and faith entered Abu Bakr's heart. He accompanied the Messenger of Allah, Allah bless him and give him peace, everywhere whether in travel or in Mecca. When The Messenger of Allah, Allah bless him and give him peace, was sent as a Prophet at the age of forty, Abu Bakr who was then thirty-eight embraced Islam and believed in the Messenger of Allah, Allah bless him and give him peace. When Abu Bakr reached forty, he prayed (My Lord! Arouse me that I may give thanks for the favour wherewith Thou hast favoured me…)”.
from this we can see that the revelation of this verse is about a man coming of age. Ibn kathir has commented and explained on the exact words about reaching forty in this verse.
(and reaches forty years)
meaning, his complete intellect, understanding, and patience reach the level of maturity. It has also been said that usually one will not change his ways once he reaches the age of forty.
40 YEARS AND THIS UMMAH (significant thoughts in light of quran and sunnah)
it is proven with authentic reports that previous generations/ummah lived for more than 1000 years. it is reported Adam (A.S) lived as much and Nuh (A.S) spent 950 years calling people to Allah. when it comes to this ummah, it is narrated ;
prophet (PBUH) said :
“The lifespan for my Ummah is from sixty years to seventy years and very few surpass this” [sunan tirmidhi]
it is also reported that our beloved prophet (PBUH) passed away at the age of 63.
and there are some narrations that Abu Bakr (R.A), Umar (R.A) and Ali (R.A) all passed away between 60 - 70 years of age.
40 years of age is a very important milestone in the life of a man (woman). keeping in mind the average lifespan of sixty-seventy years, one who reaches 40 years of age completes about two-thirds of his (her) average lifespan; thereby meaning that he (she) enters into the last third of his (her) life.
apart from achieving this percentage of lifespan, a man becomes strong (both mentally and physically), he reaches to a stage of maturity, and is able to understand and tackle the highs and lows of all spheres of the life in a reasonable and wise manner. we know that Allah started sending the revelations to our beloved Prophet (PBUH) when he reached 40.
in the translation of the verse to english, the translators have used words/phrases such as maturity, full strength, grew-up to manhood and fully grown to describe the arabic word used. thus it becomes more clear of the significance of that age as it all points towards the prime or peak age as you have mentioned.
WHY 40 ?
the number 40 (be it an age, count of days or something else) is mentioned numerous times in islam. like Musa(A.S) roaming the desert for 40 years and spending 40 days on mount sinai. prophet Ibrahim(A.S) spending 40 days in the fire. Prophet suleiman (A.S) and Prophet (A.S) each ruled for 40 years etc.
(note : these are taken from history books and some reports are Israeli narrations, so caution applies)
even in authentic hadith the number 40 is mentioned, as in the hadith Sunan Ibn Majah 3377.
considering all this, we are bound to a belief that there is a definite wisdom behind it and it is just we may not fully understand it.
the most important thing to be done when one reaches the age of 40 is that he/she should make a re-assessment of his own personality, thank Allah for His favors and pray for parents & off-springs. the repentance to Allah should be renewed again (this should be done always,even when you are 13) and one should recite the supplication mentioned in the verse above and abandon all his (her) wrong acts (if any) from that point onwards.
As Allah azzawajal says in the very next verse ;
They are those from whom We shall accept the best of their deeds and overlook their evil deeds. (They shall be) among the dwellers of Paradise, a promise of truth, which they have been promised. [46:16]
may Allah the mighty and sublime grant us mercy and guide us to the straight path.
ALLAH KNOWS BEST