Question

Assalaamu Alaikum wrwb,

You said "Knowledge of tajweed is fardh kifayaah, meaning some of the Muslim community must know it, and its application is fardh 'ain, required by all Muslims (men and women) who have the complete Qur'an or part of it memorized, even if only one surah." Where are you getting this hukm from? I have read replies from other scholars saying that the hukm of Tajwid is emphasized sunnah. I will be very grateful.
Jazak Allahu Khair.

Answer

Wa alaikum assalaam wa rahmatu Allahi wa barakatuh.

That particular quote is a translation from the book Hidaayah Al-Qaaree ilaa tajweed kalaam Al-Baaree by Ash-Sheikh Abdulfattah Al-Mursafee, but it is found in other books on tajweed in the same wording (in Arabic).  Many scholars of tajweed, including Imam Ibn Al-Jazaree (An-Nashr), Ash-Shayraazee, As-SuyooTee, and An-Nawawi to name a few, state that applying tajweed in recitation of the Qur’an is waajib (required).

The book “Fann AT-Tarteel wa ‘Uloomuh” by Ash-Sheikh Ahmed At-Taweel, published by the King Fahd Printing Complex , confirms that applying tajweed rules, without necessarily knowing the names of the rules is waajib for all reading a portion of the Qur’an (volume one p. 190).  Some rules are much more important to apply than others.  Some rules are considered as required, such as the application of the articulation points of the letters within human limits and other rules that are more detailed are considered as beautification of recitation, but not required. 

The learning of the names of rules and all that is entailed in definitions and studying them is ruled fardh kifaayah, as stated previously by the scholars of tajweed (p. 193 Fann At-Tarteel wa ‘Uloomuh).

Ibn Al-Jazaree stated in his poem with the basic rules of tajweed:

And taking tajweed is a absolute necessity, who does not [read] correctly the Qur’an is sinful         
Because the Deity revealed it with it [tajweed]

All of the numerous books by scholars of tajweed that we looked at stated the same ruling.

Please refer to the PDF document:  Why should we read the Qur’an with tajweed for more details on the ruling of tajweed by the scholars of tajweed.

Also, you may want to read the following question and answer to give you more insight as to the specific areas of what is required and what is considered as much better, but not required: http://www.abouttajweed.com/q2060102.htm

Insha’ Allah this gives you more insight into the ruling.

Wa iyyaakum

Wa assalaam alaikum wa rahmatu Allah.