וְלֹא־יָכְלָ֣ה עוֹד֮ הַצְּפִינוֹ֒ וַתִּֽקַּֽח־לוֹ֙ תֵּ֣בַת גֹּ֔מֶא וַתַּחְמְרָ֥ה בַחֵמָ֖ר וּבַזָּ֑פֶת וַתָּ֤שֶׂם בָּהּ֙ אֶת־הַיֶּ֔לֶד וַתָּ֥שֶׂם בַּסּ֖וּף עַל־שְׂפַ֥ת הַיְאֹֽר׃
Ne pouvant le cacher plus longtemps, elle lui prépara un berceau de jonc qu’elle enduisit de bitume et de poix, elle y plaça l’enfant et le déposa dans les roseaux sur la rive du fleuve.
Rashi on Exodus
ולא יכלה עוד הצפינו AND SHE COULD NO LONGER CONCEAL HIM, because the Egyptians calculated the period from when he (Amram) took her back. She, however, bore him after a term of six months and one day — for a woman who gives birth to a child in the seventh month may do so in incomplete months (i. e. the seventh month of pregnancy may not be completed) (Niddah 38b) — and they (the Egyptians) made enquiry regarding her at the end of nine months (the normal term of pregnancy, but in this case three months after the child’s birth; therefore “she could no longer conceal him”).
Sforno on Exodus
ותשם בסוף, a place where the people passing would not see her deposit the basket; in spite of this, the reason why she chose the reeds was that she thought the decree of babies having to be thrown into the river had been fulfilled by placing him within the river’s domain.