http://revach.net/article.php?id=3560

Section: Moadim   Category: Pesach
Kotzker Rebbe: Why The Third Shift Of The Korban Pesach Didn't Make It
The Mishna in Pesachim (5:7) says that the Korban Pesach was brought in three shifts.  One third of the Yidden waiting to bring their Korban Pesach filled the azara each shift.  While the Kohanim shected the korbanos, the Yidden would say Hallel over and over, until the Kohanim finished the avodah of every person's Korban.  The Mishna says "MiMeihem Shel Kas Shlishis Lo Higia LAhavti... Mipnei SheAma Muatim", the third shift never even reached Ahavti (in Hallel) the first time around because there were so few people in that group.

The Kotzker Rebbe quips that has they reached "Ahavti", had they reached the lelvel of loving Hashem, they would have been in one of the first two groups and not waited until the end!