Why was Yocheved no longer able to hide Moshe?
Rashi and Targum Yonasan: He was born after six months - thereby enabling her to hide him for three months. The Egyptians first came to inspect nine months after his parents' marriage.
The word "Hatzefino" has an unusual Dagesh in the letter Tzadi (for instance, in the similar word "Hakrivo" (Vayikra 7:16) there is no Dagesh - CS). What does it tell us?
Maharal (Gevuros Hashem Ch. 17, p. 79): The Dagesh emphasizes that she went to great effort to conceal her baby - but was unsuccessful.
Noach had overlaid his ark with pitch, both on the inside and on the outside (Bereishis 6:14). Why did Yocheved use clay and pitch?
Rashi #1: She used clay on the inside, so the Tzadik Moshe should not be subjected to the repugnant smell of pitch. 1
Rashi #2 (to Bereishis 6:14): Because, as opposed to Noach's boat, which had to withstand the turbulence of the Flood, the waters of the Nile were calm - in which case, strengthening the inside with pitch was unnecessary.
Da'as Zekenim, Hadar Zekenim: She used clay on the outside, so it will look like reeds of the river bank, which get dirty from the mud. Pitch is black. If it were on the outside, it would have been discernable that it was a man-made ark.
Gur Aryeh (to Bereishis 6:14): Was this sufficient reason to diminish the insulation protecting her baby? Refer to 2:3:2.1:1.(While Rashi to Bereishis 6:14 gives a second reason why Noach needed pitch both inside and out (answer 2:3:2:2), our Rashi does not cite it.)
Why did Yocheved opt to place it specifically among the reeds beside the river?
Seforno: She hid the basket among the reeds from view of passers-by - specifically among the reeds, so as to fulfill Pharaoh's decree (of casting the savior into the river), which could now be cancelled.
Rashbam: She hid it among the reeds, from the view of passers-by, but not from the view of people bathing in the river. 1
Rashbam: Which explains why Pharaoh's daughter spotted it, but not her maidservants.
What did Yocheved expect to gain by casting the baby into the Nile, seeing as a Yisrael who found him would not dare save him for fear of Pharaoh, whereas a Mitzri would be bound to empty the basket into the Nile? Meanwhile, Moshe would choke to death for lack of fresh air?
QUESTIONS ON RASHI
Rashi writes: "She could not hide him any longer - ... They checked after her at the end of nine [months]." The Gemara (Sotah 12a) explains how the Egyptians would take along one of their own babies and prod him to cry, causing the (concealed) Jewish babies to cry along with him.... Was this really necessary?
Maharal (Gevuros Hashem Ch. 17, p. 79): That which is "Sod," hidden and secret, will tend to remain so. Anything that can be revealed by natural efforts, is not a "Sod." Because this method existed, the Egyptians were able to discover the hidden babies - even without utilizing it.
Rashi writes: "[She smeared] pitch on the outside, and mud on the inside, so that the Tzadik would not smell the offensive odor of pitch." Was this sufficient reason to diminish the insulation protecting her baby?
Gur Aryeh (to Bereishis 6:14): Would Moshe's mother have put him in danger merely due to the bad smell? Our Pasuk does not address steps necessary to avert danger, but rather describes extra precautions taken by Moshe's mother. (Otherwise, why mention any smearing at all; surely she must have put some water-proofing on the basket!) According to our Rashi, pitch would have been appropriate on the inside as an extra precaution, but she refrained from doing so due to the bad smell. (According to the other approach in Rashi to Bereishis 6:14, pitch was not needed on the inside, even as an extra precaution, because the water was calm.)