Is there a specific number of times that one should visit Makkah?
Question

                I was recently told by two sources
  that in the Sunnah there is a reference to fulfilling an Islamic precept that one should
  visit Mecca 7 times in ones life and Jerusalem once.  Could you please help me verify
  this as I have been unable to.
  Thank you very much for your help.
Praise be to Allah.Whoever makes any claim about Islamic teachings 
  should produce sound evidence. Allaah says (interpretation of the meaning):
“… Say: ‘Produce your proof 
  if you are truthful.’ ” [al-Baqarah 2:111]
So it is not permitted to accept anyone’s 
  opinion without evidence or proof. What evidence is there that a Muslim should 
  visit Makkah seven times and Bayt al-Maqdis (Jerusalem) once in his lifetime?!
Allaah has made it a duty to perform Hajj once 
  in a lifetime. The Prophet  (peace and blessings 
  of Allaah be upon him) said: “O people, Allaah has made Hajj a duty upon 
  you, so perform Hajj.” A man asked, “(Should we do it) every year, 
  O Messenger of Allaah?” but he remained silent. The man asked the question 
  three times, then the Prophet  (peace and blessings 
  of Allaah be upon him) said: “If I say yes, it will be obligatory for you, 
  and you will not be able to do it.” Then he said: “Do not push me 
  to tell you more than I have told you. Those who came before you were destroyed 
  because they asked too many questions and argued with their Prophets. If I command 
  you to do something, then do as much of it as you can, and if I forbid you to 
  do something, then leave it well alone.” (Reported by Muslim, 
  2380)
Allaah says (interpretation of the meaning): “And 
  perform properly (i.e., all the ceremonies according to the ways of Prophet 
  Muhammad), the Hajj and ‘Umrah (i.e., the Pilgrimage to Makkah) for Allaah…” 
  [al-Baqarah 2:196]
The person who performs Hajj and ‘Umrah 
  once in his lifetime does not have to do them again, but it is encouraged to 
  repeat Hajj and ‘Umrah, because the Prophet  
  (peace and blessings of Allaah be upon him) said: “Follow up one Hajj or 
  ‘Umrah with another, for they eliminate poverty and sins as the fire eliminates 
  dross from iron, gold and silver. An accepted Hajj brings no less a reward than 
  Paradise.” (Reported and classed as hasan by al-Tirmidhi, al-Sunan, 
  738). The Muslim who is capable and healthy is encouraged not 
  to stay away from the Ancient House (i.e., the Ka’bah) for too long, as 
  Abu Hurayrah reported that the Messenger of Allaah  
  (peace and blessings of Allaah be upon him) said: “Allaah says: ‘If 
  a slave to whom I have given good health and ample provision does not come to 
  visit Me once every five years, he is indeed deprived.’” (Reported 
  by Ibn Hibbaan and others; see Saheeh al-Jaami’, 1909). 
All of the above reports indicate that frequent visits to Makkah 
  are encouraged, but they are not obligatory.
As far as visiting Bayt al-Maqdis (Jerusalem) 
  is concerned, if a Muslim never visits it in his lifetime, there is nothing 
  wrong with that. There are no obligatory acts of worship connected with it, 
  but it is the third of the great Mosques which a Muslim is permitted to travel 
  to visit; it is not permitted to travel to any other place for the purpose of 
  prayer and worship, except these three mosques. The Prophet  
  (peace and blessings of Allaah be upon him) said: “No one should set out 
  on a journey (of pilgrimage) except to three mosques: Masjid al-Haram [in Makkah], 
  the Mosque of the Messenger of Allaah  (peace and 
  blessings of Allaah be upon him) and Masjid al-Aqsaa [in Jerusalem].” (Reported 
  by al-Bukhaari, 1115). The reward for praying in Masjid al-Aqsaa 
  will be multiplied over the reward for praying in any other mosque, apart from 
  Masjid al-Haram in Makkah and Masjid al-Nabi  (peace 
  and blessings of Allaah be upon him) (The Prophet’s Mosque) in Madeenah. 
  The author of Mughni al-Muhtaaj said: “It has been proven that prayer 
  in Masjid al-Aqsaa is worth five-hundred times more than other prayers, as was 
  reported by Ibn ‘Abd al-Barr; al-Bazzaar said: its isnaad is hasan.”
 Jaabir ibn ‘Abd-Allaah said: “The Messenger of Allaah 
   (peace and blessings of Allaah be upon him) said: 
  ‘One prayer in this Mosque of mine is better than a thousand prayers in 
  any other mosque except for al-Masjid al-Haram, and one prayer in al-Masjid 
  al-Haram is better than one hundred thousand prayers offered elsewhere.’” 
  (Reported by Imaam Ahmad; see also Saheeh al-Jaami’, 3838).
And Allaah knows best.