Database
[{language:"tamil"},{language:"english"},{language:"hindi"},{language:"hindi"},{language:"english"},{language:"english"}]
Query
db.collection.aggregate([{$group:{_id:null,vids:{$push:"$$ROOT"}}},{$project:{vids:{$concatArrays:[{$filter:{input:"$vids",cond:{$eq:["$$this.language","hindi"]}}},{$filter:{input:"$vids",cond:{$eq:["$$this.language","tamil"]}}},{$filter:{input:"$vids",cond:{$eq:["$$this.language","english"]}}}]}}},{$unwind:"$vids"},{$replaceWith:"$vids"},{$limit:4}])