When did he go to Achav?
'Rashi': In Melachim I, 22:2 it says that it was in the third year, i.e. from when [Achav] sent Ben Hadad.
Malbim: It was after the majority of Yehoshafat's kingship passed, in his 17th year. He reigned for 25 years.
What was the enticement of Ramos Gil'ad?
'Rashi': It is like it says in Melachim I, 22:3 "Ramos Gil'ad is ours." Refer to Melachim I, 22:3:1:1,2.
Malbim: A Mesis always shows [to the enticed party] some benefit. If so, we must say that [Achav] offered [to Yehoshafat] some wage [for joining with him]. The verses here and in Melachim imply unlike this! This is why Chulin 4b says that he enticed him through Zevichah, i.e. food and drink. 1
Malbim (citing Chulin 4b): It asks that perhaps he enticed him with words, but rejects this; Hasasah is not through words (that is Pituy). It asks from "Ki Yesisecha Achicha" (Devarim 13:7), and answers that it is via food and drink. It asks from "va'Tesiseni Vo Leval'o Chinam" (Iyov 2:3), and answers that Hashem is different (it is not proper to say Pituy regarding Him).
