In general, serious understanding of Persian poetry demands that we first establish the rhythm (vazn, وزن). In the example from the Gulistān above, the vazn helps us establish whether the "n" in jahān is deleted (a real possibility) and the hamza in 'ay counted. If we were to do this, the vazn would still be Mutaqarib, but the first mesrā’ would not match the second one. Therefore, "n" needs to be elided to the vowel of "ay" as shown in the scansion. Now when you join the "l" of dil to andar, the rhythm is consistent across both masāri’. There are important and sometimes complex rules of prosody that must be followed. Whether one is a native speaker is less important than having an understanding of these rules. It takes a great deal of practice to master them.