Rasool Allah^-saww did not keep long hair, as is generally believed. However, only once Rasool Allah^-saww did not get a haircut and that was due to the treaty of Hudaybiyya. In 9 A.H., Rasool Allah^-saww came to Makkah with the intention of performing Hajj but it was rescheduled to the next year, as per the conditions of the Treaty of Hudaybiyya. Therefore, Rasool Allah^-saww observed the conditions of Ihraam and let his^-saww hair grow and got his^-saww head hair shaved after completing the Hajj. This is the only time Rasool Allah^-saww had long hair, reaching the level of his^-saww ear lobe and that was not by choice but due to the conditions, imposed by the nonbelievers of Makkah. Rasool Allah^-saww had to agree to these conditions in order to the save the lives of believing men and women who were residing in Makkah, under the control of non-believers, e.g., http://hubeali.com/article/hudaybiyya-treaty/.

مُحَمَّدُ بْنُ يَحْيَى عَنْ أَحْمَدَ بْنِ مُحَمَّدِ بْنِ عِيسَى عَنِ ابْنِ أَبِي نَصْرٍ عَنْ عَلِيِّ بْنِ أَبِي حَمْزَةَ عَنْ أَبِي بَصِيرٍ قَالَ قُلْتُ لِأَبِي عَبْدِ اللَّهِ ( عليه السلام ) الْفَرْقُ مِنَ السُّنَّةِ قَالَ لَا قُلْتُ فَهَلْ فَرَقَ رَسُولُ اللَّهِ ( صلى الله عليه وآله ) قَالَ نَعَمْ قُلْتُ كَيْفَ فَرَقَ رَسُولُ اللَّهِ ( صلى الله عليه وآله ) وَ لَيْسَ مِنَ السُّنَّةِ قَالَ مَنْ أَصَابَهُ مَا أَصَابَ رَسُولَ اللَّهِ ( صلى الله عليه وآله ) يَفْرُقُ كَمَا فَرَقَ رَسُولُ اللَّهِ ( صلى الله عليه وآله ) فَقَدْ أَصَابَ سُنَّةَ رَسُولِ اللَّهِ ( صلى الله عليه وآله ) وَ إِلَّا فَلَا

Muhammad Bin Yahya, from Ahmad Bin Muhammad Bin Isa, from Ibn Abu Nasr, from Ali Bin Abu Hamza, from Abu Baseer who said,

‘I said to Abu Abdullah^-asws, ‘The parting (of the hair) is from the Sunnah?’ He^-asws said: ‘No’. I said, ‘So did Rasool-Allah^-saww part (the hair)?’ He^-asws said: ‘Yes’. I said, ‘How is it that Rasool-Allah^-saww parted and it is not from the Sunnah?’ He^-asws said: ‘The one who is hit by what Rasool-Allah^-saww was hit by would be parting just as Rasool-Allah^-saww parted, so he would have abided by the Sunnah, or else, so no’.

قُلْتُ لَهُ كَيْفَ ذَلِكَ قَالَ إِنَّ رَسُولَ اللَّهِ ( صلى الله عليه وآله ) حِينَ صُدَّ عَنِ الْبَيْتِ وَ قَدْ كَانَ سَاقَ الْهَدْيَ وَ أَحْرَمَ أَرَاهُ اللَّهُ الرُّؤْيَا الَّتِي أَخْبَرَهُ اللَّهُ بِهَا فِي كِتَابِهِ إِذْ يَقُولُ لَقَدْ صَدَقَ اللَّهُ رَسُولَهُ الرُّؤْيا بِالْحَقِّ لَتَدْخُلُنَّ الْمَسْجِدَ الْحَرامَ إِنْ شاءَ اللَّهُ آمِنِينَ مُحَلِّقِينَ رُؤُسَكُمْ وَ مُقَصِّرِينَ لا تَخافُونَ

I said to him^-asws, ‘How is that?’ He^-asws said: ‘Rasool-Allah^-saww, when he^-saww was turned away from the House (Kabah after the treaty of Hudaybiyya)[1], and he^-saww had ushered the sacrificial animal, and wore the Ihraam, Allah^-azwj Showed him^-saww the vision in which Allah^-azwj Informed him^-saww of it in His^-azwj Book [48:27] Certainly Allah had Endorsed to His Rasool the vision with the truth: you shall enter the Sacred Masjid, if Allah Pleases, in security, (some) having their heads shaved and (others) having their hair cut, you shall not be fearing.

فَعَلِمَ رَسُولُ اللَّهِ ( صلى الله عليه وآله ) أَنَّ اللَّهَ سَيَفِي لَهُ بِمَا أَرَاهُ فَمِنْ ثَمَّ وَفَّرَ ذَلِكَ الشَّعْرَ الَّذِي كَانَ عَلَى رَأْسِهِ حِينَ أَحْرَمَ انْتِظَاراً لِحَلْقِهِ فِي الْحَرَمِ حَيْثُ وَعَدَهُ اللَّهُ عَزَّ وَ جَلَّ فَلَمَّا حَلَقَهُ لَمْ يُعِدْ فِي تَوْفِيرِ الشَّعْرِ وَ لَا كَانَ ذَلِكَ مِنْ قَبْلِهِ ( صلى الله عليه وآله ) .

Thus, Rasool-Allah^-saww knew that Allah^-azwj would be Fulfilling for him^-saww with what He^‑azwj had Shown him^-saww. So, from then onwards, he^-saww preserved the hair (did not cut) which was upon his^-saww head when he^-saww was in Ihraam, awaiting to shave it off in the Sanctuary, since Allah^-azwj Mighty and Majestic has Promised him^-saww. So, when he^‑saww did shave it off, (and) did not repeat the preservation of the hair, nor was that from his^-saww own self’.^[2]

وَ مِنْ كِتَابِ نَوَادِرِ الْحِكْمَةِ عَنِ الصَّادِقِ ع عَنْ آبَائِهِ عَنْ عَلِيٍّ ع قَالَ: لَا تَحْلِقُوا الصِّبْيَانَ الْقَزَعَ.

And from the book ‘Nawadir Al Hikmah’ –

‘From Al-Sadiq^-asws, from his^-asws forefathers^-asws, from Ali^-asws having said: ‘Do not shave the young boys like the broken clouds’’.[3]

وَ مِنْ تَهْذِيبِ الْأَحْكَامِ عَنْ أَبِي عَبْدِ اللَّهِ ع قَالَ: أُتِيَ النَّبِيُّ ص بِصَبِيٍّ يَدْعُو لَهُ وَ لَهُ قَنَازِعُ فَأَبَى أَنْ يَدْعُوَ لَهُ وَ أَمَرَ بِحَلْقِ رَأْسِهِ.

And from the book ‘Tahzeeb Al Ahkaam’ –

‘From Abu Abdullah^-asws having said: ‘Someone came to the Prophet^-saww with a young boy for him^-saww to supplicate for him, and there were tufts of hair for him. He^‑saww refused to supplicate for him and instructed with shaving off his head’’.[4]

وَ عَنِ الصَّادِقِ ع قَالَ: أَلْقُوا الشَّعْرَ عَنْكُمْ فَإِنَّهُ يُحَسِّنُ.

And from Al-Sadiq^-asws having said: ‘Cast (comb) the hair away from you, for it is better’’.^[5]

وَ مِنْ كِتَابِ اللِّبَاسِ عَنْ أَيُّوبَ بْنِ هَارُونَ قَالَ: سَأَلْتُ أَبَا عَبْدِ اللَّهِ ع كَانَ رَسُولُ اللَّهِ ص يَفْرُقُ شَعْرَهُ

And from ‘Kitab Al Libaas’ – from Ayoub Bin Haroun who said,

‘I asked Abu Abdullah^-asws, ‘Did Rasool-Allah^-saww used to part his^-saww hair?’

قَالَ لَا وَ كَانَ شَعْرُ رَسُولِ اللَّهِ ص إِذَا طَالَ طَالَ إِلَى شَحْمَةِ أُذُنِهِ.

He^-asws said: ‘No, and the hair of Rasool-Allah^-saww, when he^-saww grew it long, it was long up to his^-saww ear lobes’’.^[6]

عَنْ عَمْرِو بْنِ ثَابِتٍ عَنِ الصَّادِقِ ع قَالَ: إِنَّهُمْ يَرْوُونَ أَنَّ الْفَرْقَ مِنَ السُّنَّةِ

From Amro Bin Sabit,

‘From Al-Sadiq^-asws, he (the narrator) said, ‘They are reporting that the parting (of the hair) is from the Sunnah’.

قَالَ مَا هُوَ مِنَ السُّنَّةِ

He^-asws said: ‘It is not from the Sunnah’.

I said, ‘They are claiming that the Prophet^-saww parted (his^-saww hair)!’

قَالَ مَا فَرَقَ النَّبِيُّ ص وَ مَا كَانَتِ الْأَنْبِيَاءُ تُمْسِكُ الشَّعْرَ.

He^-asws said: ‘The Prophet^-saww did not part (his^-saww hair), and the Prophets^-as did not used to withhold (keep long) hair’’.^[7]

وَ عَنْهُ ع قَالَ: مَنِ اتَّخَذَ شَعْراً فَلَمْ يَفْرُقْهُ فَرَقَهُ اللَّهُ بِمِنْشَارٍ مِنْ نَارٍ وَ كَانَ شَعْرُ رَسُولِ اللَّهِ ص وَفْرَةً لَمْ يَبْلُغِ الْفَرْقَ.

And from him^-asws having said: ‘One who takes (keeps long) hair, but does not part it, Allah^-azwj will Part him with a saw of Fire; and hair of Rasool-Allah^-saww was abundant, not reaching the parting’’.^[8]

السرائر مِنْ جَامِعِ الْبَزَنْطِيِّ عَنِ الْحَسَنِ بْنِ عَلِيِّ بْنِ يَقْطِينٍ عَنْ أَبِيهِ عَنْ أَبِي الْحَسَنِ الْأَوَّلِ ع قَالَ سَمِعْتُهُ يَقُولُ‏ إِنَّ الشَّعْرَ عَلَى الرَّأْسِ إِذَا طَالَ أَضْعَفَ الْبَصَرَ وَ ذَهَبَ بِضَوْءِ نُورِهِ وَ طَمُّ الشَّعْرِ يُجَلِّي الْبَصَرَ وَ يَزِيدُ فِي ضَوْءِ نُورِهِ‏.

(The book) ‘Al Saraair’, from ‘Jamie’ of Al Bazanty, from Al-Hassan Bin Ali Bin Yaqteen, from his father,

‘From Abu Al-Hassan^-asws the 1^st, he (the narrator) said, ‘I heard him^-asws saying: ‘The hair upon the head, when it is long, weakens the sight, and does away with illumination of his Noor, and covering the hair polishes the sight and increases in illumination of his Noor’’.^[9]

[1] http://hubeali.com/article/hudaybiyya-treaty/

[2] Al Kafi – V 6 – The Book of Outfits and the Beautification and the Magnanimity Ch 34 H 5

[3] Bihar Al-Anwaar V 73 – The book of Etiquettes – Ch 4 H 1 / 3

[4] Bihar Al-Anwaar V 73 – The book of Etiquettes – Ch 4 H 1 / 4

[5] Bihar Al-Anwaar V 73 – The book of Etiquettes – Ch 4 H 1 / 13

[6] Bihar Al-Anwaar V 73 – The book of Etiquettes – Ch 4 H 1 / 14

[7] Bihar Al-Anwaar V 73 – The book of Etiquettes – Ch 4 H 1 / 15

[8] Bihar Al-Anwaar V 73 – The book of Etiquettes – Ch 4 H 1 / 12

[9] Bihar Al-Anwaar V 73 – The book of Etiquettes – Ch 4 H 10