Safe fenugreek sprouting in a jar?
Per the Foodsafety.gov, since sprouts must necessarily be grown in warm and humid conditions, they are unique among produce items in presenting a risk of food born illness.


  Since 1996, there have been at least 30 reported outbreaks of
  foodborne illness associated with different types of raw and lightly
  cooked sprouts. Most of these outbreaks were caused by Salmonella and
  E. coli.


You will have to decide whether you feel this level of risk is acceptable to you.

They suggest the only real mitigation is thoroughly cooking the spouts.

Savvy Vegetarian suggests:


  
  Start with very clean containers and utensils, preferably glass - no plastic.
  Rinse the seeds or beans before soaking.
  Use purified water for rinsing and soaking.
  Keep the soaking seeds in a cool place away from direct light.
  Soak for no more than 12 hours.
  Drain and rinse once or twice while soaking seeds.
  Wash your hands before handling the sprouts.
  Rinse several times a day while growing sprouts.
  


However, I am not sure I can concur with their assertion that these precautions render spouts as safe as any other produce, as only spouts are grown in warm, moist conditions.