Is there any recommended length of the beard?

There is no recommended or specified length of the beard, because nothing to that effect has been narrated from the Prophet (peace and blessings of Allaah be upon him). What has been reported is that the beard should be left as it is.

Muslim (2344) reported that Jaabir ibn Samurah (may Allaah be pleased with him) said: “The Messenger of Allaah (peace and blessings of Allaah be upon him) used to have a very hairy beard.”

An-Nisaa’ (5232) reported from al-Baraa’ that he (peace and blessings of Allaah be upon him) had a thick beard; according to another report, he had a bushy beard; according to another report, he had a wide beard.

Some scholars permit cutting the hair of the beard that exceeds the amount that may be grasped in the fist, because Ibn ‘Umar did this; but most of the scholars regard this as makrooh, which is more apparent because of the reports referred to above.

Al-Nawawi said: the best is to leave it as it is and not touch it or shorten it at all. (Tuhfat al-Ahwadhi, 8/39).

– As for the hadeeth, “He used to reduce the length and width (of his beard)” – this is a false and fabricated hadeeth.

See al-‘Ilal al-Mutanaahiyah by Ibn al-Jawzi, 2/686

Allaah says (interpretation of the meaning):

“Indeed in the Messenger of Allaah (Muhammad) you have a good example to follow for him who hopes for (the Meeting with) Allaah and the Last Day…” [al-Ahzaab 33:21]

“And whatsoever the Messenger (Muhammad) gives you, take it; and whatsoever he forbids you, abstain (from it).” [al-Hashr 59:7]

Shaykh Ibn ‘Uthaymeen (may Allaah preserve him) said: The definition of the beard as stated by the scholars of (Arabic) language is: the hair of the face, jawbone and cheeks, in the sense that all the hair on the cheeks, jawbone and chin is part of the beard and removing any of it is counted as a sin, because the Messenger (peace and blessings of Allaah be upon him) said: “Let your beards grow,” “Leave your beards alone,” “Let your beards increase,” “Let your beards be full.” This indicates that it is not permissible to remove anything from the beard. But the sin may vary in degree – shaving the beard is worse than shortening it, because it is a more obvious contradiction of the Sunnah.

For more information, see Question # 1189.

And Allaah knows best