Is
    there any recommended length of the beard?
Question

                is there any recommended length of the
      beard traceable from Prophet Muhammad SAAW
Praise be to Allah.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