don't wait to start singing

 תשורי מראש אמנה

עתידין ישראל לומר שירה לעתיד לבוא, שנאמר: (תהלים צח, א)שירו לה' שיר חדש כי נפלאות עשה.

ובאיזה זכות אומרים ישראל שירה?

בזכות אברהם שהאמין בהקדוש ברוך הוא, שנאמר: (בראשית טו, ו) והאמין בה', היא האמונה שישראל נוחלין בה, ועליו הכתוב אומר: (חבקוק ב, ד) וצדיק באמונתו יחיה.

הוי, תשורי מראש אמנה.

Last week I posted R' Chaim's chiddush that even if a person is sure Hashem is going to do a miracle and save him, he can only sing shirah after the fact.  "V'ani b'chasdicha batachti yageil libi b'yeshuasecha," but nonetheless, "Ashira la'Hashem ki gamal alay," not beforehand. 

The SHL"H has a different POV based on the Midrash above.  עתידין ישראל לומר שירה לעתיד לבוא -- why the double language?  If shirah is something that Bnei Yisrael are עתידין in the future going to sing, then obviously it will take place עתיד לבוא?  

The SHL"H explains that tzadikim don't wait for the miracle to happen -- their trust in Hashem is so great that they start singing shirah in anticipation of what's going to come.  

In the future, when we have that level of emunah, עתידין we will sing shirah לעתיד לבוא, on what will happen, without waiting for it to actually occur.  תשורי מראש אמנה - the shirah will be מראש, before the event occurs, because of our  אמנה, our faith in Hashem.

Bnei Yisrael at Yam Suf were not at that level, which is why (al pi peshuto shel mikra, not like the Mechilta we learned last week) they sang shira only after the fact.  "Ya'yaaminu ba'Hashem ub'Moshe avdo" afterwards, but their emunah was not complete enough beforehand.

The complaint (Meg 10b) of מעשה ידי טובעין בים ואתם אומרים שירה is not because G-d was per se opposed to the malachim singing shira.  G-d was asking why the delay until now; why the wait until the Egyptians were drowning to start singing instead of starting beforehand.

Based on this approach, the SHL"H says a fantastic pshat in this gemara regarding Chizkiyahu:

 ביקש הקב"ה לעשות חזקיהו משיח וסנחריב גוג ומגוג אמרה מדת הדין לפני הקב"ה רבש"ע ומה דוד מלך ישראל שאמר כמה שירות ותשבחות לפניך לא עשיתו משיח חזקיה שעשית לו כל הנסים הללו ולא אמר שירה לפניך תעשהו משיח לכך נסתתם (Sanhedrin 94) 

The reason Hashem did not appoint Chizkiyahu to be Mashiach is because Chizkiyahu לא אמר שירה לפניך -- he didn't sing shirah לפניך, before the fact, but waited only until afterwards.  In the times of Mashiach we will be singing in anticipation of the miracles, not only after they happen.  

This also explains, writes the SHL"H, why when discussing the shirah Bnei Yisrael sang the pasuk uses the feminine voice, "ha'shira ha'zos," but when talking about the song of Miriam and the women, it uses the masculine voice, "va'taan lahem Miriam."  Bnei Yisrael's faith was incomplete, "tashash kocham k'neikeivah" in their midah of emunah, but the women went of of Mitzrayim carrying their "tupim u'mecholos," musical instruments, ready to sing even before the Yam split.  They had the gevurah the men were lacking, the emunah of "zechus nashim tzidkaniyos" which was the catalyst for the geulah.