Please note that this is not a complete list, but rather a general guide.

On Grammar (nahw):
1. al-Kitāb by Sībawayhi
2. Ma‘ānī al-Qur’ān by al-Farrā’
3. al-Muqtadab by al-Mubarrad
4. al-Usūl fi al-Nahw by Ibn al-Sarrāj
5. al-Mufassal by al-Zamakhsharī
6. al-Kāfiyah by Ibn al-Hājib
7. al-Alfiyyah by Ibn Mālik
8. Mughnī al-Labīb by Ibn Hishām

On Morphology (sarf):
1. al-Tasrīf by al-Māzinī
2. al-Tasrīf by Ibn Jinnī
3. Nuzhat al-Tarf fī ‘ilm al-Sarf by al-Maydānī
4. al-Mumti‘ fī al-Tasrīf by Ibn ‘Usfūr
5. al-Shāfiyah by Ibn al-Hājib

Dictionaries (Ma‘ājim al-Alfādh):

(Arranged according to articulation points)
1. al-‘Ayn by al-Khalīl ibn Ahmad
2. Tahdhīb al-Lughah by al-Azharī

(Arranged alphabetically – starting with first root letter)
1. al-Jīm by Abu ‘Umar al-Shaybānī
2. Jamharat al-Lughah by Ibn Durayd
3. Mu‘jam Maqāyīs al-Lughah by Ibn Fāris
4. Asās al-Balāghah by al-Zamakhsharī
5. al-Misbāh al-Munīr by al-Fayyūmī

(Arranged alphabetically – starting with last root letter)
1. Tāj al-Lughah by al-Jawharī
2. Lisān al-‘Arab by Ibn Mandhūr
3. al-Qāmūs al-Muhīt by al-Fayrūzābādī
4. Tāj al-‘Arūs by al-Zubaydī

Thesauri (Ma‘ājim al-Ma‘ānī):
1. al-Gharīb al-Musannaf by Ibn Salām
2. al-Alfādh by Ibn al-Sikkīt
3. al-Alfādh al-Kitābiyyah by al-Hamadānī
4. Jawāhir al-Alfādh by Qudāmah ibn Ja’far
5. Fiqh al-Lughah by al-Thālibī
6. al-Mukhassas by Ibn Sīdah

On Rare words in the Qur’ān (Gharīb al-Qur’ān):
1. Tafsīr Gharīb al-Qur’ān ibn Ibn Qutaybah
2. Mufradat alfādh al-Qur’ān by al-Isfahānī

On Rare words in the Hadīth (Gharīb al-Hadīth):
1. al-Fā’iq fī gharīb al-Hadīth wa al-Athar by al-Zamakhsharī
2. al-Nihāyah fī gharīb al-Hadīth wa al-Athar by Ibn al-Athīr

On Philology (Fiqh al-Lughah):
1. al-Khasā’is by Ibn Jinnī
2. al-Sāhibī by Ibn Fāris
3. Fiqh al-Lughah by al-Tha’ālibī
4. al-Muzhir by al-Suyūtī

On common solecisms and correct usages:
1. Mā talhanu fīhī al-‘Awām by al-Kisā’ī
2. Islāh al-Mantiq by Ibn al-Sikkīt
3. Adab al-Kātib by Ibn Qutaybah
4. al-Fasīh by Tha‘lab
5. Lahn al-‘Āmmah by al-Zubaydī
6. Tathqīf al-Lisān by Ibn Makkī al-Siqlī
7. Durrat al-Ghawāmid fī Awhām al-Khawāss by al-Harīrī

Allāhumma ‘allimnā mā yanfa’unā, wa infa’nā bi mā ‘allamtanā.
Oh Allāh, teach us what will benefit us, and benefit us with what You have taught us.

Ameen.

[Courtesy of the Arabic Gems blog]