Strengthening the Memory.

Frankincense (‘Lubbaan’ in Arabic) is an aromatic resin produced by a certain genus of trees grown mainly in Yemen, Somalia and Oman, and is traditionally used in perfumes, incense and as a medicine. The resin is tapped and allowed to harden, before being powdered. It is most commonly very light yellow in colour and is discussed as one of the medicines used in the treatment of forgetfulness.

[Page 337 of Healing with the Medicine of the Prophet (sallallahu alayhi wasallam) - Darussalam 2003]

While a number of Hadith have been presented in this above book which suggest the use of Frankincense was promoted by the Blessed Companions of Rasool'Allah (sallallahu alayhi wasallam) for forgetfulness, I have been unable to verify their sources as of yet or confirm if they are Sahih.

According to texts translated from the works of Ibn al Qayyim (rahimullah), the application of Frankincense as a remedy has a simple and clear reasoning. Mild amnesia, forgetfulness or a weak memory of past experiences, events or words results from a corrupt humour somewhere in the body. This corrupt humour affects different parts of the brain, causing ill-disposition, particularly in people with cold, damp temperaments. This condition produces defective memory and thus blocks the brain’s natural ability to retain messages in sequence or to store information.

Frankincense, which contains the opposite attributes, thus helps to repair and balance the bodily humours. This helps ultimately to remove the blockage and restore the memory. Amongst the other numerous benefits of frankincense; it aids the treatment of tuberculosis, stomach ache and diarrhoea, and it helps the digestion, helps expel wind, relieve eye sores / refreshes the eyes, treats infections and helps heal cuts and bruises when used in a bandage. It also helps treat a speech impediment (both tongue-tie and stuttering). Burning frankincense helps repel mosquitoes and other flying insects.

The brothers at the TibbeNabawi.org site say that a 'tea' can be made by tying the frankincense resin in a small cloth like a piece of muslin, and adding it to boiling water. Let the water simmer for around 5 min before extracting the frankincense and allowing the tea to cool down before drinking.

Both the resin and the oil can be purchased online. 

My recommendation is food-grade Hujari frankincense which can be purchased here - http://freeyoursenses.co.uk/#/yellow-hojari/4555599604

You can find more information about frankincense here - http://en.wikipedia.org/wiki/Frankincense, including on how frankincense is graded - http://freeyoursenses.co.uk/#/grading/4555298751

A weak memory may also sometimes be due to dryness and can be overcome by increasing the intake of water and other fresh, clean, pure fluids.

Remedies for Forgetfulness which are substantiated by the Sunnah.

I would encourage all those who are looking to improve their memory to use the remedies below in combination first.

Hijama.

A very beneficial treatment for weak memory is Hijama (wet cupping) and although I have not come across any Sahih Hadith directly pertaining to the use of Hijama for improvement of the memory, there are plenty of strong sources praising the excellence of Hijama in general and that it is a cure for a wide range of illnesses. There are also strong evidences from the Sunnah that Hijama was used by the Messenger of Allah (sallallahu alayhi wasallam) to cure ailments of the head.

It was narrated by Jabir bin 'Abdullah (rahimullah) that he paid Al-Muqanna a visit during his illness and said, "I will not leave till he gets cupped, for I heard Allah's Apostle (sallallahu alayhi wasallam) saying, "There is healing in cupping [Hijama]." 
Sahih al Bukhari Volume 7, Book 71, Number 600.

It was also narrated by Ibn Abbaas (radhi Allahu anhu) that the Prophet (sallallahu alayhi wasallam) was cupped on his head for an ailment he was suffering from while he was in a state of Ihram. at a water place called Lahl Jamal located on the road to Makkah. Ibn 'Abbas further said: Allah s Apostle was cupped on his head for unilateral headache while he was in a state of Ihram.

Sahih al Bukhari Volume 7, Book 71, Number 602

Caution will be required when applying Hijama on the head. Cupping at the back of the head (on the occipital bone) carries a high risk of causing further memory loss. Excessive cupping on other parts of the head may also cause the same, and Allah Azzawajjal knows best. The Hijama practitioner should take extra care and not remove a lot of blood. The top middle  part of the head (crown) is the Sunnah point - Sahih al Bukhari Vol. 3, Book 29, Hadith 62

You can find out more about the benefits of Hijama by clicking here.

Ruqyah.

The established Hadith confirm that the Recitation of the Qur'an was performed by the Messenger of Allah (sallallahu alayhi wasallam) to treat people (mainly those inflicted with Magic or Evil Eye) and that there is no harm in reciting it yourself as long as it is only from the Qur'an;

A'isha (radhi Allahu anha) narrated that Allah's Apostle (sallallahu alayhi wasallam) used to treat with a Ruqyah saying, "O the Lord of the people! Remove the trouble The cure is in Your Hands, and there is none except You who can remove it (the disease)." 
Sahih al Bukhari Volume 7, Book 71, Number 640.

For strengthening the memory and progressing in Islamic Knowledge, the following verse of the Holy Qur’an should be recited (in Arabic) an odd number of times everyday after the Salaah and thereafter make supplication to Allah Azzawajjal with the intention that He strengthen your memory;

“My Lord! Expand for me my breast [with assurance]. Ease my task for me. Remove the knot [impediment] from my tongue. So that they may understand my speech.”

[Qur'an 20:25-28]