וְאַתָּ֖ה וַעֲבָדֶ֑יךָ יָדַ֕עְתִּי כִּ֚י טֶ֣רֶם תִּֽירְא֔וּן מִפְּנֵ֖י יְהוָ֥ה אֱלֹהִֽים׃
Mais toi et tes serviteurs, je sais que vous ne rendrez pas encore hommage au Dieu éternel."
Sforno
כי אני הכבדתי, even though Moses had said; “I know that you do not yet relate with awe and reverence to G’d,” (9,30) he thought that even if he does not humble himself to G’d because of G’d’s greatness, at least he should do what G’d says seeing that he has no choice, and can no longer withstand the cumulative effect of the plagues. He had arrived at this conclusion when he noted the words ה' הצדיק, “the Lord is the Just One.” However, when he found out that all these pious words notwithstanding Pharaoh continued to oppose G’d’s will in spite of the fact that he found it impossible to cope with the plagues, Moses had come to the conclusion that warning Pharaoh of an impending plague was an exercise in futility. This is why G’d had to tell him at this stage that already during the sixth plague (9,12) He had stiffened Pharaoh’s heart so that ordinary rules of psychology could no longer be applied to this man. The purpose was to enable G’d to demonstrate more miracles so that maybe some Egyptians would be moved by what they experienced to become penitents. If so, the Israelites in the future would be able to tell their children of the greatness of G’d’s miracles. This in turn would convince mankind that G’d loved His creatures and was very patient with them, giving them opportunities to mend their ways. This is why the warning to Pharaoh was in place although it would prove ineffectual. G’d’s plan was
Or HaChaim
ואת לב עבדיו, and the heart of his servants, etc. The reason G'd also had to harden the heart of Pharaoh's advisers was so that they would not urge him to release the Israelites. G'd had to do so in order to bring the plagues not only on Pharaoh but on the whole nation. If Pharaoh had been the only one punished, this would not have made an impact on the people. Although G'd had not mentioned this detail to Moses at the beginning of his mission, and He had spoken only of hardening Pharaoh's heart at that time, He had told Moses the essential part of what would happen. Perhaps G'd wanted to explain to Moses at this stage that not only one man was obstinate, i.e. Pharaoh, but also his servants. He may have been prompted to do so now because of Moses' gratuitous remark in 9,30 that both Pharaoh and his servants had not yet developed true fear of the Lord. Moses' comment had indicated that he had not previously understood the word "Pharaoh" to include also Pharaoh's entourage. Therefore G'd explained to him that the obstinacy of the servants could also be explained by the same phenomenon as that of their master, i.e. that G'd had interfered with their normal decision-making process. Up until now, Moses had assumed that the servants were naturally obstinate whereas Pharaoh had only remained obstinate because G'd had interfered. G'd was at pains to correct Moses' error.
Rashi
טרם יהיה בארץ WAS NOT YET IN THE EARTH — Wherever טרם occurs in the Scriptures it means “not yet” and does not mean “before”. It cannot be made into a verbal form, saying הטרים as one says הקדים (verbal form of קדם) and this passage proves that this is the meaning and not "before" as well as another (Exodus 9:30), כי טרם תראון “that ye do not yet fear the Lord”. Therefore you must explain this verse also thus: “No plant of the field was yet in the earth” at the time when the creation of the world was completed on the sixth day before man was created, and וכל עשב השדה טרם יצמח means “and every herb of the field had not yet grown”. But as regards the third day of creation about which it is written “The earth brought forth etc.” this does not signify that they came forth above the ground but that they remained at the opening of the ground (i. e. just below the surface) until the sixth day (Chullin 60a).
Rashi
[Shmuel] had not yet known Adonoy. He had not yet recognized the nature of the prophetic voice.7He was thus unfamiliar with the ways ‘ה calls man, and he therefore thought that the voice was Eili’s. Every time the word 'טֶרֶם' appears in Scripture, it means 'not yet,' as rendered by the Targum 'עַד לָא' [not yet]. It does not mean 'before.' This verse proves it. And another [proof of this] is the verse כִּי טֶרֶם תִּירְאוּן which is rendered as "that you do not yet fear,"8Shemos 9:30. is a more explicit verse proving this. Also, וְכֹל שִֹיחַ הַשָֹּדֶה טֶרֶם יִהְיֶה בָאָרֶץ ["all plants of the field were not yet on the earth"].9Bereishis 2:5.