I\'ve found this question answered for C# and Perl, but not in the native interface. I thought this would work:
db.theColl.find( { _id: ObjectId(\"4ecbe7f9e8c
You Have missed to insert Double Quotes. The Exact Query is
db.theColl.find( { "_id": ObjectId("4ecbe7f9e8c1c9092c000027") } )